Petronella Osgood

Petronella Osgood, PhD was a scientist who worked for UNIT, acting as the scientific advisor to Kate Stewart, in the early 21st century. (AUDIO: The Sacrifice of Jo Grant)

An admirer of the Doctor, she eventually met the Time Lord during the infiltration of UNIT by Zygon invaders, which was resolved by the Eleventh Doctor joined by his tenth and war incarnations. (TV: The Day of the Doctor)

The original Osgood and her Zygon double became indistinguishable from each other to everyone else. They refused to identify which one of them was Zygon and which was human. (TV: The Zygon Invasion) Her Zygon double was later killed by, (TV: Death in Heaven; AUDIO: Narcissus; WC: The Zygon Isolation) but after a Zygon rebellion was ended peacefully, the Zygon rebel leader Bonnie took her place by assuming the form of Osgood to maintain the peace. Both Osgoods still refused to identify whether she was the human or Zygon version, but promised to identify as human or Zygon one day when no one would care anymore. (TV: The Zygon Inversion)

Early life
Petronella Osgood (TV: The Zygon Inversion) was the daughter of Frank Osgood and his partner and sister of Nova. (PROSE: For the Girl Who Has Everything) She belonged to an old UNIT family (AUDIO: Power Cell; PROSE: For the Girl Who Has Everything) and many of her relatives were science geeks, (AUDIO: Earthfall) including her father and her aunt, whose house was full of makeshift electrical connections. (AUDIO: Time of the Vulpreen)

When Osgood was young, she was part of a chess club (AUDIO: Vanguard) and took swimming lessons, although she missed out on her swimming badge due to her fear of the diving boards. (AUDIO: Open the Box) She had conflicted feelings about insects and wanted to pet spiders and learn about them, but ended up hiding under the stairs because of her phobia. (AUDIO: Hosts of the Wirrn) She was jealous of her sister, who she thought was prettier (TV: The Day of the Doctor) and who could seemingly get away with anything, but Osgood always managed to buy better Christmas presents than her. (PROSE: For the Girl Who Has Everything)

Osgood went on to study at King Henry's University in London, where she befriended Jay Roy (AUDIO: Power Cell) and achieved at least one PhD. (AUDIO: The Sacrifice of Jo Grant) She once went on a course at London Zoo and threw a tarantula out of a window. (AUDIO: Hosts of the Wirrn) Following university, she was employed by the Ministry of Defence at Dstl where she was mentored by Professor John Torrance, who held her in high esteem. (AUDIO: The Sontaran Project)

Joining UNIT
Osgood was recruited into UNIT as a technician at the Grey Archive in November or December 2011, (PROSE: For the Girl Who Has Everything) having been given a favourable reference by John Torrance (AUDIO: The Sontaran Project) and scored so highly on the IQ test that Geneva Base rejected the results three times. (PROSE: The Day of the Doctor) Kate Stewart would later remark that she hired Osgood because she was brilliant. (AUDIO: Narcissus) At her very first briefing, Kate gave a five-minute long speech on duty which Osgood memorised and was able to recite by heart. (PROSE: For the Girl Who Has Everything)

Osgood was sick in her helmet after being ejected from a submarine during basic training (AUDIO: Tidal Wave) and, in her first month, stubbed her toe on dwarf star alloy and was in pain for weeks. She impressed the higher-ups by building a universal clock out of prototype psychic paper and scavenged Nestene plastic.

On 24 December 2011, Osgood was attacked in the Grey Archive by several Sontarans and slowed her bleeding by tying part a long scarf that she found around her arm and wearing the rest of it around her neck. She was saved from a clone of Luke Rattigan by Kate Stewart, who took her to her office and decided that she would reassign her in January. (PROSE: For the Girl Who Has Everything) Osgood became UNIT's scientific advisor and typically built technology to stop the soldiers from shooting at aliens. (AUDIO: Vanguard) She became very familiar with Sontaran biology and had the opportunity to examine one or two of them. (AUDIO: The Sontaran Project)

Osgood continued to wear the scarf that she found in the Grey Archive (TV: The Day of the Doctor) and, having enjoyed reading files on the Doctor's exploits (AUDIO: Call to Arms, Tidal Wave, Hosts of the Wirrn) and accidentally memorised them, (PROSE: The Day of the Doctor) took to dressing like several of the Doctor's other incarnations in addition to their fourth. This included the Third, (AUDIO: Tidal Wave) Fifth, (AUDIO: Hosts of the Wirrn) Sixth (AUDIO: Earthfall, Hosts of the Wirrn) and Eleventh Doctors. (AUDIO: Power Cell) She and/or her Zygon duplicates would later dress like the Seventh Doctor as well. (TV: The Zygon Invasion)

As well as being a big fan of the Doctor themself, Osgood idealised several of the Doctor's companions (AUDIO: Call to Arms, Tidal Wave) and had an adventure with Sarah Jane Smith, her joint-second favourite companion, who told her about the importance of screaming when running from alien threats. (PROSE: The Day of the Doctor) She also met Alistair Gordon Lethbridge-Stewart. (AUDIO: This Sleep of Death) She read Harry Sullivan's reports on his adventures with the Fourth Doctor, including that of the Wirrn on Space Station Nerva, and described the reports as "awesome". (AUDIO: Hosts of the Wirrn)

Although Osgood did have free time, she spent most of it at work and made a hobby of looking through artefacts such as those recovered from the Silurians. (AUDIO: Retrieval) She also wrote a paper on nominative determinism with relation to alien species. (AUDIO: The Power of River Song) She hardly saw anybody outside of her job and did not have time to contemplate romance, although several people assumed that she was with Josh Carter, who sometimes flirted with her. (AUDIO: United) She was friends with and attracted to McGillop, (PROSE: The Day of the Doctor) but was happy with her job and friends and not actively looking for a relationship. (AUDIO: Narcissus)

Preventing a Nestene invasion
Osgood tracked a set of energy units falling to Earth and warned Vikram Shindi about it. (AUDIO: Vanguard) Together with Lieutenant Sam Bishop, she was deployed to the Gobi Desert in Mongolia in search of a Nestene energy unit. She had created a holographic image projector from alien technology. (AUDIO: Earthfall)

She tried to examine the energy unit using all the techniques she could think of. Kate also told her to examine one of the 3D printers. When the Nestene escaped the energy unit, she discovered that the Nestene could combine through the internet. (AUDIO: Bridgehead)

She created a new weapon to destroy the Autons and was able to free Captain Josh Carter from Nestene control. (AUDIO: Armageddon)

Tengobushi incident
After going to a pub quiz with Jay Roy, she was tasked with working out which pieces of UNIT property Lyme Industries had managed to get their hands on. She later asked Jay to help her in her work in order to work out what was kidnapping people. She started to show Jay the ropes but didn't get too far when a Tengobushi attacked. Jay decided to protect her and detonated a bomb in her flat killing himself in the process. (AUDIO: Power Cell)

Osgood went to Geneva and decided to visit local Galleries, where she was followed and attacked by Dokan. She later went with Kate and Grant Avary to investigate a set of murders on a French mountainside. She returned to Geneva to analyse some secretions and was attacked by the Tengobushi but was save by Josh. She realised that the Tengobushi wanted her for her knowledge of an alien artefact and used this to get into their ship. (AUDIO: Death in Geneva)

Osgood and Kate had to fly their plane after the Tengobushi killed the pilots during their flight. She then investigated the Kamishi energy cell in the surroundings of the Black Archive. As part of her experiments, she accidentally released some power that caused some earth tremors. After the Tengobushi released an energy barrier around the Tower of London, she released the ravens to observe their advance. During the attack, Osgood was trapped in the Archive until Josh helped get her first to the Jewellery room and then to command centre. She managed to work out how to use the energy cell and weaponised it to aid their escape. (AUDIO: The Battle of the Tower)

When they were under lock and key in UNIT's base under the Rock of Gibraltar, Osgood managed to hack into the base's computer to get their release. Whilst at Lyme's base in Antarctica she worked out a way to destroy the generator and destroyed it with the help of Dokan, who questioned her about her actions. (AUDIO: Ice Station Alpha)

Investigating the Silence
Osgood received a panicked call from Colonel Shindi who detected something near Helena Faversham's residence. While she was tracking the Silents, she kept forgetting the positive readings, and after she was attacked by the Silents, she soon forgot. She then questioned Faversham using a truth serum. (AUDIO: House of Silents)

Osgood worked on a universal translator which could understand Axons and Sontarans. She helped Bishop investigate what happened at the Faversham estate and later worked out a simplistic way of remembering the Silents: by writing stuff down. Investigating the people that went to Faversham's home, she started with the ones closest to her but they all disappeared. She and Bishop tracked Derek Butler but he was snatched from under her nose. She then looked through all the videos the people she was looking for had made and found subliminal messages to get the UK population to trust Kenneth LeBlanc. (AUDIO: Square One)

A month later, she had to brief the rest of UNIT about her solution to getting the rest to remember the Silents. She had created a pair of sunglasses which had 360-degree cameras which could give them all views of the Silents. She called the Silents "Edvard". After she stole Carter's laptop, using the same techniques the Silents used, she found a large order of guns and explosives he had ordered. She discovered from Heston where he had taken the things Josh ordered. She then tried to convince Josh not to kill LeBlanc but couldn't, so she knocked him out. (AUDIO: Silent Majority)

Osgood went with Bishop to the UNIT satellite to fix something there, but they were knocked unconscious upon arrival. Later, she started to explore the space station and found a Silent on-board. She discovered that the crew were being controlled by the Silents and had exposed the spy satellites of all the governments of the world. She tried to get the Telokni ship to stop shooting them, but couldn't and had to escape. (AUDIO: In Memory Alone)

Jastrok's revolution
Per the Earth Reptile Initiative, Osgood and Kate checked on a Silurian nest at Scafell and were attacked by Jastrok and his warriors, whom Captain Burmaster was able to keep back long enough for the two of them to escape to John Benton and Mike Yates at the White Hart. Osgood managed to contact Josh for reinforcements and, realising that the Silurians were vulnerable to sudden changes in temperature, set the beer in the cellar alight and created a backdraft. The group escaped in Bessie and the nest was destroyed, apparently by Burmaster. (AUDIO: Call to Arms)

When Kate sent Osgood to observe Project Charybdis with Jo Jones, Osgood put on a velvet jacket like the Third Doctor's and kept asking Jo to tell stories. They were locked away by Burmaster, who was under Jastrok's control, but they managed to escape and were recovered by Kate. To prevent UNIT and the Sea Devils from killing one another, Osgood sent Jo in a submersible to speak with Krelix and persuade him and his people to return to hibernation, a plan which proved to be successful. She and Kate then went to deal with Krelix's escaped hybrids. (AUDIO: Tidal Wave)

Searching for a device to control the hybrids, Osgood identified a Silurian nest in Greece as a research base and headed there with Kate, soon to be joined by Sam. Tryska used a fear trigger on Osgood to amplify her race memory, making her terrified of the Silurians and making her flee into the caves where Sam saved her. Although they were unable to find any useful technology before the base was destroyed and they were airlifted to safety by Josh, Kate did manage to upload Silurian data to the UNIT Cloud. (AUDIO: Retrieval)

Osgood and Josh had to take a mini-submersible to get close enough to Great Britain to transmat there due to pterosaurs and Krelix's hybrids besieging the island. She worked on adapting a psion cannon to release the creatures from the Silurians' control and Jo took it with her to confront Jastrok at the Houses of Parliament. Osgood, Yates, Benton and Josh went to save Jo from Kalana, who had started a nuclear countdown which Osgood managed to stop, and the creatures were released from Silurian control thanks to the device. With the threat ended, Osgood went with Jo and Sam to South America to relocate the sea creatures. (AUDIO: United)

The Auctioneers
Undercover as cyber-terrorist "Tara Winters", Osgood joined Kate, Josh and Shindi in flying to Monte Bosque to investigate what turned out to be a Dalek tracked by Sam, who had gone missing whilst looking into the Auctioneers. Their cover was blown and Osgood and Josh were locked up whilst the Dalek escaped and killed several of Maria Gonsalves's guerillas before apparently being killed in a tank. Osgood realised that it had deceived them by shedding some of its limbs and they tracked it down and defeated it. She wanted to take the Dalek mutant to try to understand it, but the Dalek self-destructed and the group were rescued by UNIT North America. (AUDIO: The Dalek Transaction)

On Hallowe'en, Osgood stayed late at work and picked up a transmission from an obsolete Voxtel satellite, part of which was in Latin. She and Josh, who told her about his experience with the Grey Man, flew to Ealdon House after Kate failed to check in with them. There, Osgood discovered that the Grey Man apparititions were caused by infrared sound sent by aliens who picked up the transmissions sent by the satellite in the 1960s. She was able to get access to the satellite and, following Kate's order, sent a message which put an end to the phenomena. (AUDIO: Invocation)

Osgood attended the New Science Conference as UNIT's delegate and ran into John Torrance, who took her to the Torrance Research Foundation and showed her his Sontaran clones. She tried to leave but was sedated by Torrance and Christine Colley using a truth serum which, thanks to Malcolm Taylor, she was immune to. By pretending to be unconscious, she overheard them talking about the Overseer. She met Merx, whose experience she sympathised with, and was rescued by the allied forces of UNIT and Marshal Skar. With the cloning project and the Foundation shut down, Osgood took Max, a monkey clone, to safety. (AUDIO: The Sontaran Project)

Following the Sontaran incident, Osgood spent a day with Sergeant Warren Culder whilst the evidence was cleared up. (AUDIO: This Sleep of Death)

Osgood and Josh were accidentally transported to a parallel universe by a transport capsule recovered from the Auctioneers and were left stranded when the capsule malfunctioned. Osgood went to collect power cables and ended up encountering that world's Osgood and Josh, who were in a sexual relationship. When Josh and her other self used the capsule, Osgood followed through the dimensional tear and later helped her other self leave, although she could not tell whether or not she would survive the trip. (AUDIO: False Negative)

The Cyber-invasion
After receiving a recording from Sam, Osgood and Kate went to save him and were given various tasks by the Overseer involving virtual reality. These tasks led Osgood to defuse a Krillitane detonator containing a corrosion virus and fly a virtual jet to Heathrow Airport to switch off an emitter. Upon completing the tasks, the Overseer allowed the two of them to speak to Shindi, who told them that a container that Malcolm could detect no signals from had appeared at Windsor Castle. Osgood opened it and found Sam inside. (AUDIO: Game Theory)

Osgood examined the virtual reality equipment at Fortress Island and realised that it was a bridge to another universe. She, Shindi and Josh used it to enter the other world and, when Kate found that she could not wake them up, they had to escape from mutated dogs, the Mechanising Worm and cyborg pigeons to the London Underground. There, they found cocooned humans and Osgood and Shindi began to be cyber-converted, establishing a link between the two dimensions. Osgood and Shindi awoke and joined Sam (AUDIO: Telepresence) as the Cybermen began to emerge through a portal.

The Cyber-Controller connected Osgood to the Cyber-Mainframe to utilise her genius in the invasion of her universe. She kept the Cybermen from fully converted Sam and Shindi and devised a plan to control humanity using the C-Control App, but Kate was able to raise a communications shield to block it. She sent the Cybermen to convert Kate to get her to bring down the shield, but she eventually managed to bring it down and raise the lockdown herself, sending the app through to every mobile phone on Earth before collapsing (AUDIO: Code Silver) due to a brainstorm of information on the Master.

Osgood planned to convert so that his TARDIS could be used to further the Cyber cause, but Josh knocked her out and escaped with him and Kate. She later restored the Cybermen that they knocked out at Whitehouse Gallery and captured the Master, putting him in a conversion unit which he pretended was effective on him. Kate restored Osgood using the corrosion virus and, after the Master drew off the dimension bridge's energy, Osgood planned to upload a patch to free humanity from their virtual conversion. (AUDIO: Master of Worlds)

Old threats
Osgood flew to the Well with the Wirrn egg that the Master left with UNIT and interviewed Shana Siddiqui for a job as an entomologist after Sergeant Brundle was infected by it. She killed several Wirrn with the mechanical arms in the lab and helped Shana hold onto her identity and keep herself from transforming into one of them, giving her tranquilisers to help with the pain when she metamorphosised. When the Wirrn attacked Windermere, Osgood flew ravens of death into the flying ones and administered a virus to Shana to kill the Queen, after which she gave her the antidote and did her best to make her life as a Wirrn as normal as possible. (AUDIO: Hosts of the Wirrn)

Whilst undertaking an experiment, Osgood was interrupted by the arrival of Vara and Norei's capsule outside the tower and worked on a translator to interpret their song. She found the harmonic cannon in the Black Archive and worked on with Vara until Kate stopped them, having learnt that the Kalvyri had attacked UNIT back in the Third Doctor's day. Osgood was against turning the two Kalvyri over to Jarrak and helped Vara sacrifice herself and destroy Jarrak's fleet to save Norei; afterwards, Osgood apologised to Kate for her insubordination. (AUDIO: Breach of Trust)

Osgood went with Kate and Josh to the Pandora Institute's facility on Mundholm, where Seth Hyer fed on her worries about being useless to her teammates in a crisis. She contacted Shindi via her confiscated hologram projector and, after working out that Seth had killed some of the Institute's clients by projecting their fears, she got Shindi to send a helicopter and used her hologram matrix to create a reflective surface with the pool's water. The Keller creature fed on itself in a feedback loop as she planned it to and disappearing under the water after greatly diminishing in size. (AUDIO: Open the Box)

New incursions
Osgood went with Kate and Josh to Abbey Marston following Sergeant Warren Calder's suicide in order to resurrect him and learn of the location of the Silurian plague that he claimed to have stolen. Calder planned to transfer his mind into Osgood's body, but it was the Static that was transferred into her before forcing Josh to bring back numerous other dead people. Kate was able to restore Osgood with Calder's help, after which she wired up explosives to destroy the stone circle when the telephone rang; to make it ring, she, Kate and Josh resurrected the Brigadier. (AUDIO: This Sleep of Death)

After receiving a report from meteorology about freak weather conditions, Osgood went with Sam to meet Mother McCracken in the Outer Hebrides to investigate the voice that came down her chimney. Osgood realised that the voice was trying to lead them to the roof, from which they could see the coordinates of the Animoi's spaceship in the North Atlantic. She and Sam persuaded the Animoi to go ahead with Kate's plan, allowing them to escape and be picked up by a rescue ship. (AUDIO: Tempest)

Osgood investigated her own murder when her body was discovered within a power station. She was suspicious of the director, known as "River Song". However the director was in fact a Wampeerix Battle Queen masquerading as River Song, intent on feeding off the energy of the Earth. The real River Song aided Kate and Osgood in defeating the Wampeerix. (AUDIO: The Power of River Song)

Operation Double
After the Eleventh Doctor called Kate from the TARDIS, Osgood excitedly joined her in meeting with him and, at his request, analysed the stone dust in the Under Gallery. She and McGillop realised that Zygons had smashed statues to enable them to hide in plain site and were attacked and duplicated, although Osgood managed to escape. In the Black Archive, the War, Tenth and Eleventh Doctors made Osgood, Kate and the Zygons forget who were humans and who were Zygons in order to allow them to create the perfect peace treaty. (TV: The Day of the Doctor)

The group spent ten hours devising the treaty and, during one of the breaks, Osgood realised that she was human and that her double was a Zygon when she handed the double her inhaler. They kept this a secret, however. (PROSE: The Day of the Doctor) Following the ratification of Operation Double and the Doctor handing over the Osgood Boxes, (TV: The Zygon Invasion) the Doctors restored everybody's memories, although this left the Zygons unconscious for a time. Osgood wrote her double a letter in which she invited her to continue using her form. (PROSE: The Day of the Doctor)

The two Osgoods administered and embodied the peace between their two races and kept an eye on the Osgood Boxes, refusing to confirm which of them was human and which was Zygon. Together, they recorded an explanation of Operation Double (TV: The Zygon Invasion) as well as a message seeking to dissuade anybody who should capture them from searching for the boxes. (TV: The Zygon Inversion)

One of the Osgoods replaced her scarf with a bow tie after meeting the Doctor. In 2014, Commander Potter told the Doctor that Osgood was away investigating a UFO sighting in Bonnybridge and that she would be devastated to learn that she had missed the Twelfth Doctor's visit. (COMIC: The Fractures)

Nightmare Scenario
After Osgood's Zygon double was killed by, (TV: Death in Heaven; AUDIO: Narcissus; WC: The Zygon Isolation) she went mad with grief and eventually went undercover to the United States. She visited Truth or Consequences where fights broke out between the humans and Zygons and informed the Doctor of the Nightmare Scenario when she was attacked by the Zygon rebels. She was captured and taken to Turmezistan where she was interrogated for information on the Zygons' whereabouts and to give UNIT the rebels' demands.

The Twelfth Doctor saved Osgood but their aeroplane was shot down by Bonnie, (TV: The Zygon Invasion) after which they took a van to South London to find her and realised after meeting Etoine that she planned on unmasking the Zygons. They saved Clara Oswald and, after the Doctor talked Bonnie out of her revolution, Bonnie took on Osgood's form to help her keep the peace. The Doctor offered to take Osgood in the TARDIS, but she turned the offer down due to her responsibilities and returned to work with her new sister. (TV: The Zygon Inversion)

A new sister
The two Osgoods put together a series of files documenting the various enemies and alien species that the Twelfth Doctor had encountered, beginning with the Zygons and Bonnie's splinter group. Other files documented his encounters with the Mire, the Sandmen, the Veil and King Hydroflax. (PROSE: The Osgood Files)

In September 2015, the two Osgoods watched Daniel Claremont's speech on global warming at Ravenscaur School whilst Kate was at the Tower of London. After Claremont was revealed to be a Sea Devil, the Osgoods recommended that Kate call the Doctor, but he was already there in his twelfth incarnation and defeated the Sea Devils without UNIT's help. (COMIC: Clara Oswald and the School of Death)

In early 2016, one of the Osgoods was in London when K2 attacked the city. She called the Twelfth Doctor, the first time she had ever done so, and joined him in the TARDIS, materialising above the London Eye as it was attacked by the robot. When the Doctor used his sonic screwdriver's red setting to destroy K2, he fell out of the TARDIS and Osgood saved him by throwing him her scarf. (COMIC: Robo Rampage)

On the eighth of March of an undisclosed year, Bonnie and Petronella struggled to work together at the UNIT lab until they discovered that Josh Carter had mysteriously disappeared the night before.

Together, they decided to investigate the Narcissus dating website and find Josh. Bonnie took the form of Jacqui McGee using her Narcissus profile and met with Jordan Love, who appeared as someone she knew during her reproductive days. However, Jordan soon discovered that she was an imposter and attacked her with a burst of energy that would’ve killed a human, but being a Zygon, she was able to survive albeit injured.

Meanwhile, Petronella prepared to confront Jordan Love on their spaceship. Bonnie tried to stop her, believing that she was more disposable than her sister. Petronella went ahead with the mission anyway and unwittingly defeated Jordan due to her complete self-reliance and contentment being toxic to them. Josh was rescued and returned to UNIT. Following these events, Bonnie and Petronella reconciled, agreeing that two Osgoods are better than one. (AUDIO: Narcissus)

Protecting the Arch
One of the Osgoods analysed the Arch after it was found by Adam Merchant's team and, when he disappeared through it, she correctly determined that he had been teleported and helped Kate and Josh search for him when he returned. When the Eleven took Kate hostage, Osgood and Josh used the Lionheart Protocol to lure him onto a UNIT plane, but he managed to escape. Osgood tried to analyse the antitoxin that the Eleven gave to the infected Merchant and believed that she needed the help of Harry Sullivan. (AUDIO: The Enemy Beyond)

Osgood and Kate flew to the Northern Territory to meet up with Harry and Naomi Cross. They tracked them down using Ros Green's social media and were forced to land by Jakernia, who later invited them, as well as Harry and Naomi, aboard her spacecraft. Harry was able to replicate the antitoxin using Ice Warrior data and the group were returned to the United Kingdom, with Osgood being worried about what the Eleven might have been up to whilst they were away. (AUDIO: Fire and Ice)

On Middle Mouse, Osgood found a way to disable the Arch using a device adapted from the Sontarans' teleport technology and assisted Kate and Josh in trying to thwart the Eleven using a hologram projector. She was later joined by Jacqui, followed by the Eleven and Ava Drake and her gang. Due to Osgood having temporarily deactivated the Arch through complex matter realignment, the Eleven was unable to make use of it and fled. (AUDIO: Eleven's Eleven)

With the Arch hidden in the Under Gallery with the Curator, whom she found familiar, Osgood set a trap for the Eleven in the National Gallery's lift which ultimately failed. The Curator took her, Kate and Josh into the J. M. W. Turner painting in which the Arch was hidden and Osgood prepared to destroy it with a disruptor to keep it from falling into the Eleven's hands, but Jacqui fell through it and the Eleven was captured. (AUDIO: The Curator's Gambit)

Vulpreen and the Void World
Osgood worked for three months to better understand the Arch in the hopes of realigning it and bringing Jacqui back. She and Jimmy Tan were accidentally teleported aboard Hasper's Battle TARDIS when he came for the Eleven and the Arch and learnt about the Vulpreen. Jacqui returned through the Arch with Orgus, whom Kate had to shoot and kill to save Osgood and Jimmy, and the Arch was later stolen by the Eleven. (AUDIO: The Man From Gallifrey)

After Naomi recognised Director Prast as a Dominator, Osgood and her attempted to surveil Portstone New Town with a Cyberman omniscope whilst Kate and Harry went undercover. They met Junaid Mirza and used a glider to enter the supposed town which they found was a slave camp. Osgood reprogramed a Quark, whom she named Quentin and whom she and Naomi missed after the Dominators were defeated and Quentin returned to his storage pods with the other Quarks. (AUDIO: Power of the Dominators)

Jacqui pulled Osgood through a time fracture when temporal anomalies appeared around the Arch at Royal Arsenal and they arrived in a future where humans and the Vulpreen were at war. Osgood realised that Jacqui had been brainwashed during her imprisonment on the Void World and tricked her into taking a message for Kate when she left her to be killed by Sorka. Osgood was saved by Private Jane Huff and returned to her own time where she sealed the fracture with a temporal modulator. (AUDIO: The War Factory)

Osgood was appalled with Josh for ordered a bombstrike to destroy the Arch after it opened given that Kate had been taken inside by a Vulpreen Commander. The two of them managed to get past the Vulpreen and the Eleven and passed through the Arch where they were reunited with Kate and returned to Earth. The bombstrike hit the Arch shortly afterwards, inadvertently giving it the power to free the Vulpreen. (AUDIO: Ten Minutes in Hell)

The Vulpreen invasion
Accompanied by Jimmy and several other UNIT soldiers, Osgood boarded the UK Space Agency's Starseeker to investigate an unusual asteroid which they found to be a Vulpreen spacecraft. The Starseeker was destroyed after Osgood and the UNIT soldiers landed on the craft in a shuttle; there, Osgood and Jimmy were taken prisoner by Commander Krillen and subjected to psychic attacks to prepare them for interrogation. Osgood managed to free herself and Jimmy from their cell and they returned to Earth through an arch, followed by Vulpreen. (AUDIO: The Vulpreen Encounter)

Osgood created an air tunnel to allow her, Kate and Jimmy to escape underwater whilst Jacqui distracted the Vulpreen and was captured. After being rescued by Naomi, Osgood went with her to inspect a new arch at Alberta and found Yang Li freezing in the snow, giving her a survival suit to warm up. She saved Naomi with a chrono-gauge when she was trapped by a temporal snare and watched as the Axons began to emerge from the arch. (AUDIO: By Jacqui McGee)

With Kate and Jimmy having disappeared, Osgood and Li went to Norway to investigate Josh's report of rapidly-growing trees, which she found was due to Axonite contamination. She realised that Axos could not absorb hydrogen and had UNIT release liquid hydrogen near the arches when it began its feeding process, during which she travelled through the arch to save Kate from Axos using bleach. Osgood attended Kate's small memorial for Jacqui and, afterwards, watched Lord Varliss's message as the Vulpreen invasion of Earth began. (AUDIO: Axos Unleashed)

Osgood oversaw the missions to surround the hundreds of arches and planned to spread the effects of the Eleven's time field inhibitor to leave the arches vulnerable using the Internet. She said goodbye to Josh using the holographic projector and helped the Eleven repair the inhibitor after it was damaged, but it failed. She was reunited with Josh and helped Kate escape by helicopter from Varliss, from whom Osgood learnt that the Vulpreen were being assisted by. (AUDIO: Time of the Vulpreen)

Continued career
One of the Osgoods was picked up from UNIT HQ by the Twelfth Doctor while the other had gone out to pick up some coffee. The Doctor took this Osgood on her first trip in the TARDIS and asked her to prepare a briefing for him after they arrived on Nayspiel, the capitol mega-city of the Alliance. They stopped a plot by the Lisban corporation to invade the planet Albensi. The Doctor returned Osgood to UNIT HQ just in time to see the return of her sister. (AUDIO: Field Trip)

In October 2016, one Osgood mailed the other based on a large increase of transmitter activity coming from Saxon Heights. They realised that this was Missy and later had UNIT crash into the school. However Osgood later confirmed to Kate Stewart that they had lost her. (PROSE: Yes, Missy)

One of the Osgoods was the commanding force behind UNIT's shutting down of Harmony Shoal Institute, following an anonymous tip off. (TV: The Return of Doctor Mysterio)

The Doctor invited her on a trip in the TARDIS to a planet who were in the midst of planning an invasion. Osgood witnessed the debate and had some suggestions to improve policy. A couple of people tried to stop the proceedings and the Doctor asked her to chase after one of them. She was eventually caught and interrogated by one of them and discovered that the assailant was trying to stop the invasion. Osgood was then placed undercover to help the Doctor plant a virus in a private company's servers. She used one of her gizmos to jam the signals to help the Doctor talk to the invaders. (AUDIO: Field Trip)

When Jenny's bowship crashed into the Terrance Dicks Library, one of the Osgoods examined the craft only to wind up infected with the white energy from the Void. Spreading the infection to the other UNIT troops, she was slaved to the will of a rogue Type 1 TARDIS before the Doctor managed to have the Type 1 stand out. (COMIC: The Lost Dimension)

Kate's absences
In 2017, after surviving the Grand Serpent's attempt to assassinate her, Kate immediately called Osgood and told her that she was going dark before destroying her mobile phone. (TV: Survivors of the Flux) Kate remained largely absent until 2021. (WC: 14684 UNIT Field Log; TV: The Vanquishers)

On 10 May, 2020, at around 18:30 pm, Osgood and her Zygon duplicate watched The Zygon Invasion, an episode from the ninth series of Doctor Who. (WC: The Zygon Isolation)

In 2022 Kate disappeared (AUDIO: Recruits) due to the psychic virus that had infected the Thirteenth Doctor and was erasing people who had had contact with her. (AUDIO: Salvation) Osgood took over as Chief Scientific Officer of UNIT and spoke to the hosts of The Blue Box Files at the Black Archive in the hopes that they would help with UNIT's fading records of the Doctor. She took a particular interest in Abby McPhail, whom she offered a place at UNIT. (AUDIO: Recruits)

As more and more of the population disappeared, Osgood led experiments on one of the ghosts that had started appearing, insisting that they had to carry on despite Abby's concerns about the tests. (AUDIO: Requiem) Osgood subsequently disappeared herself, (AUDIO: Rescue) but the Doctor and Cleo Proctor later restored everybody who disappeared. (AUDIO: Salvation)

Personality
Osgood was a "fan" of the Doctor and knew of many of his previous incarnations. She would pick iconic items (i.e. multi-coloured scarf, bow tie) from the incarnations she knew of and wore them herself. (TV: The Zygon Inversion) When asked by the Twelfth Doctor if she would like to travel with him, she was so excited that she had to use her inhaler. (TV: Death in Heaven) Osgood would become saddened if she learned she missed a chance to see the Doctor; one of her fellow scientists even stated she would be disheartened to learn the Doctor had regenerated again after she had just started mimicking his previous self's fashion. (COMIC: The Fractures)

Osgood was very intelligent. She alone was able to work out the reason why the Zygons smashed the statues in the Under Gallery. (TV: The Day of the Doctor) She also surprised the Twelfth Doctor by correctly presuming that Missy was the Master regenerated into female form: UNIT kept files on all past Prime Ministers, including the Master. (TV: Death in Heaven) She also came up with a hypothetical plan for invading Earth by killing the Doctor by shooting him between the eyes for each regeneration, never allowing him to talk. (TV: The Zygon Inversion)

She managed to figure out whether she or her Zygon doppelganger was the real Osgood after the Tenth and Eleventh Doctors, joined by the War Doctor, jumbled their minds, making them unable to determine their own species, in an attempt to facilitate negotiation of the ultimate peace treaty. She discovered this when her Zygon counterpart suffered an asthma attack, motivating her to pass her asthma inhaler to the other Osgood. (TV: The Day of the Doctor)

Osgood had a sister to whom she negatively compared herself. Missy observed that she had little confidence in herself. (TV: Death in Heaven) Osgood proved capable of such courage, and was willing to fight back and go to the rescue. (TV: The Day of the Doctor, The Zygon Invasion|The Zygon Inversion)

Appearance
Osgood dressed according to the Doctor's fashion senses from various incarnations, choosing to wear a similar scarf to that worn by the Fourth Doctor. (TV: The Day of the Doctor, COMIC: Robo Rampage) She also wore an olive green moleskin overcoat and a burgundy bow-tie similar to those worn by the Eleventh Doctor. (AUDIO: Tidal Wave) She also wore a shirt with question marks on the collars, like the Fourth, Fifth and Sixth Doctors. When the Nightmare scenario occurred she wore items of clothing similar to the Seventh Doctor when he visited Maiden's Point. (TV: The Zygon Invasion) On at least one occasion she wore a costume inspired by the Sixth Doctor. (COMIC: The Lost Dimension) When Kate sent Osgood on a mission with Jo Jones, she wore a velvet jacket and a frilly shirt like the Third Doctor. (AUDIO: Tidal Wave)

She had tattoos of the Doctor's various incarnations across her body, and wanted to add all of their faces eventually. (PROSE: The Day of the Doctor)

A parallel Osgood was surprised at how mousy her other self looked. (AUDIO: False Negative)

Behind the scenes

 * On 24 July 2014, Ingrid Oliver appeared in-character as Osgood in a video thanking fans for helping the official Doctor Who Twitter account reach one million followers.
 * Osgood appears as a background character in the London scene and the hidden Black Archives location in the Doctor Who level pack in LEGO Dimensions.

Family ties

 * In DWM 484, Steven Moffat admitted his intention when writing was for Osgood to be the daughter of UNIT soldier Tom Osgood from the Third Doctor era. However, he did not want to state this definitively in the script so fans would be able to form their own interpretations.
 * In the audio story Power Cell, Osgood responds to the suggestion that she had an uncle who used to run around shooting aliens with "something like that". This is consistent with the theory that Tom Osgood is Osgood's father and with the lack of definitive confirmation.
 * In the audio story Call to Arms, John Benton says Osgood is "just like him", and she automatically assumes he means someone specific other than the Doctor — "you mean, just like my..." — but her inquiry cut short before she names them.
 * In the short story For the Girl Who Has Everything, however, Osgood's father is named Frank, though this confirmation does not negate the possibility of Tom Osgood still being related to Petronella.