K9 Mark I, or K9 Mark 1, (TV: Regeneration) was a portable computer originally owned by Professor Frederick Marius, who considered the robot dog his "best friend". Together, they conducted advanced medical research at the Bi-Al Foundation. When the Fourth Doctor and Leela arrived at the Foundation, Leela quickly became enamoured of the dog. The professor eventually gave the dog to the time travellers as thanks for defeating the Swarm. (TV: The Invisible Enemy)
The Mark I was particularly associated with and protective of Leela. Therefore, when she elected to remain on Gallifrey, he also chose to stay behind with her. (TV: The Invasion of Time) Nevertheless, he occasionally left Leela's side when he was sent on solo missions by the Time Lords. During these adventures he travelled in a spacecraft the Time Lords built especially for him called K-NEL. (PROSE: K9 and the Missing Planet, et al.)
He eventually came into the service of Lady President Romana II when Romana tapped Leela as her personal bodyguard. Together, Leela and K9 went on many missions together at Romana's request. He was a vital link between the two ex-companions of the Doctor, since he could easily and silently interface with Romana's K9 unit. (AUDIO: Square One et al.)
The unit's ultimate fate was considerably unclear, since two radically different accounts existed. According to one, he was utterly destroyed in an explosion and Leela adamantly refused to have another model built in his place. (AUDIO: Imperiatrix) However, the other held that after K9 lived through many adventures of his own in the service of the Korven, Alistair Gryffen's Space-Time Manipulator plucked him out of time and brought him to 21st century Earth, where he was forced to self-destruct when facing the Jixen, engage his regeneration unit, and become K9 Mark 2. Thereafter he accepted a boy named Starkey as his new master and had several adventures on Earth in the 2050s. (TV: Regeneration)
Professor Frederick Marius had a dog called Kelso. He couldn't take Kelso with him to his new workplace at the Bi-Al Foundation, so he constructed K9 six months before leaving Earth, working on it day and night. He used all the latest technology. The heart of the machine was Professor Marius' medical computer. A state-of-the-art intraresponsive brain app was added inside which allowed K9 to talk. Furthermore, a huge general knowledgepool was added into the brain. (PROSE: One Man and His Dog)
When he first met Leela, Professor Marius said only that he "had K9 made up" — not that he "created" or "designed" the unit — because weight restrictions did not allow him to bring his real dog from Earth into space. (TV: The Invisible Enemy)
One account claimed that K9 may have owed his existence to a temporal paradox. Far from inventing the dog himself, Marius copied the remnants of one of the versions of K9 created by the Doctor and given to Sarah Jane Smith. (PROSE: Tautology)
Meeting the Doctor and Leela
In the year 5000 AD, K9 aided Marius in scanning the Fourth Doctor for the Swarm inside him. He later fought off the humans infected by the Swarm on Bi-Al and on Titan Base, saving the Doctor and Leela's lives on several occasions. Marius offered K9 to the Doctor to travel in the TARDIS as Y5K compliance issues (PROSE: The Gallifrey Chronicles) and weight restrictions made him unable to take K9 back to Earth with him. (TV: The Invisible Enemy)
On the TARDIS
Shortly after being taken aboard the TARDIS, K9 was damaged. The Doctor sought to repair him and kept referring to him as an "it", much to Leela's chagrin. His repair work got interrupted by the Doctor and Leela being intercepted to Fetch Priory via a Relative Continuum Displacement Zone. (TV: Image of the Fendahl)
K9 became repaired and often played chess against the Doctor, frequently winning. When the TARDIS landed on Pluto, K9 became caught up in affairs and assisted the Doctor and Leela in taking down the Collector and the Company. He led the assault on the Correction Centre to rescue the Doctor and became an integral part in the eventual uprising. (TV: The Sun Makers)
The Doctor arrived on Agratis to see the Jewel of Fawton and eat a banquet. However, the Jewel had gone missing and the Judoon had been called in to reclaim it. While the Doctor searched for the Jewel's thief, Leela and K9 distracted the Judoon out of the city so the Doctor could leave; K9 connected himself to a tank and Leela hijacked a motorbike.
When the species that originally owned the Jewel were discovered, the Judoon's search was called off. Becoming much less aggressive, Leela invited them to dine at the banquet. While Leela was feasting with the Judoon, a mysterious cloaked figure kidnapped Leela and K9. (COMIC: A Rare Gem)
On E9874, he stunned one of the Tarls which entered the ship and thought it resembled a Neanderthal. He worked out that there was atypical development when they travelled in a cart. Ergu was interested in him. He recognised a complex symbolic pattern. He was damaged when Gethal kidnapped Leela. He analysed the symbols and found a way to destroy the beacon. (AUDIO: The Exxilons)
K9 stopped an assassin from killing the Doctor, which led the Doctor to devise a plan to find out who wanted him. As part of the Doctor's plans, K9 was reprogrammed to obey the Rocket Men leader Shandar and was fitted with a rocket to help with their raids. After the Doctor was discovered, K9 stunned the Decayed Master and Shandar. The Doctor then asked him to direct him through the asteroid field to destroy the rest of the force field generators. Howver, he couldn't do the calculations quickly because he was decrypting the codes of the prisoner and slave locks. He then generated a facsimile of the Doctor. When the Master tried to escape, K9 stalled the Master's TARDIS so he could use it to signal Galactic Heritage. (AUDIO: Requiem for the Rocket Men)
K9 piloted the TARDIS to the coordinates where Marshall had said he had traced the Master and Leela. The Doctor asked K9 to trace Leela through the Death Match's arena. He met with the Red Knight who found him funny and his rocket blew up. This damaged him considerably and shortly afterwards he had to escape from a set of locusts. He rescued Marshall from the Red Knight and showed him the loading bay, realising that the machinery there was used to heal Leela. He then helped the Doctor to reverse the transmat and got them out of the arena and back to the TARDIS. (AUDIO: Death Match)
K9 effected a materialisation on Krelos and changed the TARDIS control room. He then became infected by the strange particulates in the room. He started to calculate something and ignored the Doctor's commands. He tried to fight the infections. K9 exited the TARDIS and tried to climb after the Doctor and Leela. Re-entering the TARDIS, he told the Doctor that the TARDIS was malfunctioning. He helped the Doctor zone in on Geralk's signal. He reported to his new masters that the Doctor and Leela had escaped. Now fully controlled, he set the TARDIS on a course for Telos. (AUDIO: The Fate of Krelos)
The Doctor had changed the course K9 had programmed so that the TARDIS travelled back in time. This weakened the Cybermen's control over K9. When the TARDIS fell off a cliff, K9 was damaged and the Doctor noticed that there was a Cybermat in his brain. He repaired himself and left the TARDIS. He entered the hibernation chamber with the Robot Drone which the Doctor controlled to stop the cyber nanites from infecting the TARDIS. This rewrote time, meaning K9 was no longer infected. (AUDIO: Return to Telos)
He started to act strangely when he and Leela landed on Westtropi III. This included shooting Leela's knife out of her hand and telling her not to explore. It was later revealed that he was being controlled by a Time Vampire. (AUDIO: The Time Vampire)
When the TARDIS landed on the R1C, K9 was plugged into the failing systems of the ship in order to reboot it. He helped the Doctor and the Minyans uncover a conspiracy by the Oracle to rule over the Minyans as a god. He participated in the defeat of the Oracle. (TV: Underworld)
K9 participated in the Doctor's plan to put the Vardans in a time loop. In order to effect this, the Doctor had himself inducted as Lord President on Gallifrey. He had K9 destroy the transduction barrier, allowing the Vardans to travel along wavelengths and partially materialise on the planet. When the Vardans, and the Sontarans who followed them, were defeated, Leela chose to stay behind, having fallen in love with Andred. K9 chose to stay with his "mistress" to look after her. She asked him if the Doctor would be lonely without them, but he could only reply that there was "insufficient data", which saddened both. (TV: The Invasion of Time)
On Gallifrey, both K9 and Leela socialised with the Gallifreyans by attending functions. The duo had become celebrities due to their origins off-world, which was unusual to the "sheltered" Gallifreyans. However, K9 and Leela's friendship had become "frosty", and when K9 attended an unveiling of a statue of himself in the Panopticon due to him helping defeat the Sontarans, Leela didn't attend, thinking it was "stupid". K9, by this time, had begun a conversation with K9 Mark II in E-Space. K9 told Mark II about Leela's pregnancy, and he and Mark II discreetly squabbled with each other until news of the Fourth Doctor's fall and subsequent regeneration reached Gallifrey and Mark I suggested that they should "bury the hatchet" at such a trying time. (PROSE: Jealous, Possessive)
Though K9 remained on Gallifrey to "protect" Leela, he was occasionally used by the Time Lords for various solo missions. Towards this end, they gave him a specially built space vessel called K-NEL that only he could control, which gave him freedom of movement in space, but not time. (PROSE: K9 and the Time Trap, et al.)
K9 was briefly reunited with the Doctor, now in his seventh incarnation, who stopped by to see how Leela's development had progressed. The Doctor took the identity tag from K9's collar as a memento. (PROSE: Affirmative)
After the destruction of Romana III's Gallifrey during the War in Heaven, K9 became trapped in the Doctor's TARDIS. He was ultimately freed by the Eighth Doctor and sent on a mission to the planet Espero (PROSE: The Gallifrey Chronicles) in search of Madame Xing, who had previously offered to bring the Doctor's memories back. (PROSE: Halflife)
K9 was with Leela on Gallifrey for many years, but it was only after the disappearance of Andred that she and her K9 met Romana II and her K9. Despite the fact that the two K9 units did not get on well and competed with each other, (AUDIO: Weapon of Choice, The Inquiry) they frequently networked together and allowed easy communication between their respective mistresses. (AUDIO: Square One)
Romana sent K9 after Leela when she went to the Outsiders as Romana wanted her to do something. He was given mission information from Romana's K9. He pretended to be a criminal from Fifth Galaxy and looked for information on Free Time. In a bar, he met Mephistopheles Arkadian as he had more information on the group. He used his information on Shakespeare to enter the human enclave. He realised that the Timonic Fusion Device was a contrivance. (AUDIO: Weapon of Choice) He went with Leela to a fake temporal summit as a spy to find out if any delegates were part of the Free Time movement. He was able to get the codes to enter guarded parts of the platform with the help of his counterpart on Gallifrey. As he was part of the systems, he was the reason why Leela could remember the negated timelines. (AUDIO: Square One)
He was called to the Inquiry into Romana's actions on Gryben and was programmed to speak on K9 Mark II's behalf. He was sent to the Archives to find information on the Timonic Fusion Device and data bomb disarmament. He was asked by Romana to deactivate his other self to allow the bomb to detonate. (AUDIO: The Inquiry)
K9 accompanied Leela to the catacombs of the Capitol and helped her come to terms with Andred's betrayal. When Leela went missing, he contacted K9 Mark II to tell Romana of this. Shortly afterwards, he became infected by Pandora and only reacted when the other K9 talked. (AUDIO: Lies)
He was tasked to do the examination of the mysterious body that landed on Davidia as he wouldn't be infected by the potential contagion. He worked out that the mysterious body was known to Leela and Romana. He identified the body to be that of Wynter and thought that it was an incorrect analysis. He started to hear Pandora's voice. He recorded Wynter's actions when he became the mysterious body. (AUDIO: Pandora)
He helped Leela to investigate the bombings at the Academy. He theorised that Darkel knew about the bombings from the evidence he had obtained. With Narvin's help he investigated the Academy system to find information. He went to the Time Scaphe's to find any bombs. Whilst scanning he accidentally set off the bomb. He was destroyed in the resulting explosion. Leela was heartbroken, but refused to allow a duplicate unit to be built in his place. (AUDIO: Imperiatrix)
Agent of the Korven
Though Leela and Time Lord technology had confirmed that the explosion had utterly destroyed K9, (AUDIO: Imperiatrix) other accounts confusingly stated that at some point, K9 Mark I, very much alive, became an agent of the Korven. (TV: Hound of the Korven) During this period, he had a number of adventures whose details were not well recorded. For example, the Mark I was known to have gone to the second planet of the Montoon system and observed the Sea of Brains. He also liberated the Anubians from the Huduct. Furthermore he saved the Glomb Tenklept from being eaten by a Yakoclaw. (TV: Curse of Anubis)
Later, he went to the year 50,000 and met Zanthus Pia, head of the Galactic Peace Commission, whom he later saw murdered at the hands of Ahab, a Jixen emissary, and his three guards. As K9 was a witness, the Jixen attacked him. (TV: The Bounty Hunter) The Jixen were pulled to 2050 London via a Space-Time Manipulator and tried to warn the humans about a Korven invasion. However, they couldn't speak English and the humans believed they were attacking them. K9 was likewise pulled across time through the STM and attacked the Jixen. After a brief battle, he realised his power was running low, and as a last resort to protect the humans, K9 self-destructed, destroying himself and two of the Jixen. Although working for the Korven, he cared for the safety of humans and advised them to evacuate. Using his regeneration unit, the remains transformed into a new incarnation. (TV: Regeneration, Hound of the Korven)
K9 was often left behind in the TARDIS and so he saw journeying out as a treat. (TV: The Sun Makers) Despite his claims that he was not programmed to feel emotion, he did show a capacity for feeling. He sulked when Leela insulted him, and would only talk to her again after she apologised.
The Doctor described him as overbearing, arrogant and insufferable, after K9 told him there was only a 1% chance of the Doctor having a better explanation for something than him.
Bulleted list should be converted to sourced prose
The mechanics of K9 Mark I included rotating ear-probes, telescopic "eye" probe, extendable nose, flashing lights on the top and the "eye" panel, waggling tail antennae, and ticker-tape tongue. The head could also move up and down. The shell was painted in gold/grey metallic. There was a monitor screen on his left flank, though K9 rarely used this during his travels with the Fourth Doctor. Around K9's neck was a tartan collar, from which hung a silver disk. (TV: The Invisible Enemy) By the time of his liberation of the Anubians, K9 was modified so he could fly through the vacuum of space. (TV: Curse of Anubis)
K9 was capable of calculating up to 72 variables at once. He could project a simulation of the Fourth Doctor, with accurate personality and behaviour, which fooled even the Decayed Master. (AUDIO: Requiem for the Rocket Men)
K9 had a vast database inherited by his next incarnation containing data on the following aliens:
K9 claimed that he was shaped like a dog because "the human ego requires a familiar reference point to aid in adjusting to new concepts. Animal forms are comforting to the majority of humans." (PROSE: Housewarming)
Behind the scenes
- In an early draft of The Invisible Enemy, K9 was called FIDO, for "Phenomenal Indication Data Observation". (INFO: The Invisible Enemy)
- The original K9 model was designed by visual effects designer Tony Harding. One early concept was to have a small actor in a large Doberman-shaped costume; however, Graham Williams vetoed this, saying that the robot should not look like a person in a costume. The eventual design was closely based on Harding's third concept sketch. (DCOM: The Invisible Enemy)
- K9 Mark I returned in the first episode of K9. When asked by a fan for clarification Bob Baker said:
Yes this is the K9 that the Doctor left with Leela on Gallifrey. In this version he was plucked out of space and time by the STM totally at random. His self-destruct in Ep 1 to save the humans results in triggering a "regeneration unit" put there presumably by the Time Lords, but of course we're not allowed to mention that.
- K9 Mark I was the first in a seven-year run of non-human televised companions who inhabited the TARDIS, ending with the departure of Turlough in 1984. Others included K9 Mark II, Romana I, Romana II, Adric, Nyssa and, nominally, Kamelion.
- The numbers appended to K9's "marks" have narrative origin — unlike, say, Romana I, which is actually a fan assumption. The Invasion of Time ends with the Doctor pushing a box labelled "K9 MII" into the console room, which implies that the model that stayed with Leela on Gallifrey was "K9 MI". However, based on televised stories alone, there was no indication that this designation was programmed into the two units. It was later established by John Leeson's dialogue in the audio story The Inquiry and the short story Jealous, Possessive that K9 Mark I thought of himself as "K9 Mark I" and Romana's model as "K9 Mark II". Nevertheless, nothing has ever clearly indicated that the Mark I was truly "the first K9 ever built, anywhere in the universe". The designation is relative to the Doctor's perception, or to relative age amongst the K9 units eventually resident on Gallifrey.