K9 Mark I

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 for an unknown length of time. 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 build especially for him called K-NEL. (PROSE: K9 and the Missing Planet, and others)

He eventually came into the service of Lady President Romana II when Romana tapped Leela as her personal bodyguard. Together, Leela and the Mark I 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 and others)

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 its place. (AUDIO: Imperiatrix) The other held that he somehow ended up on 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)

Later models — or marks — of K9 were based on this one.

Creation
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 he was 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 it. This allowed K9 to talk. Furthermore a huge general knowledgepool was added into the brain. Professor Marius added these parts together creating K9. (PROSE: One Man and His Dog)

When he first met Leela, Professor Frederick 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, the professor 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.

The Professor offered K9 to the Fourth Doctor to travel in the TARDIS as the same weight restrictions made him unable to take Mark I back to Earth with him. (TV: The Invisible Enemy)

On the TARDIS
Sometime during his travels, he met Robin Hood. (TV: The Last Oak Tree)

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, he was reprogrammed obey the Rocket Men leader Shandar. He was fitted with a rocket to help with their raids. He told Shandar that he was in fact the fifth most wanted person in the galaxy, after, the Rani and the Terrible Zodin. After the Doctor was discovered, he stunned the Master and Shandar. The Doctor then asked him to direct him through the asteroid field to destroy the rest of the force field generators. He couldn't do the calculations quickly because he was decrypting the codes of the prisoner and slave locks. He generated the 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. He was an excellent TARDIS pilot. (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. He showed Marshall the loading bay and realised that the machinery there was used to heal Leela. He then helped the Doctor to reverse the transmat and got them out of arena and back to the TARDIS. (AUDIO: Death Match)

He effected a materialisation on Krelos and changed the TARDIS control room. He became infected after this happened 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. Leela noticed that K9 was acting strangely. Now fully controlled, he set the TARDIS on a course for Telos. (AUDIO: The Fate of Krelos)

The Doctor had changed the course he had programmed so that they 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 and K9 wasn't infected. (AUDIO: Return to Telos)

He started to act strangely when he and Leela landed on Westtropi III. This including shooting Leela's knife out of her hand and telling her not to explore. He was being controlled by a Time Vampire. (AUDIO: The Time Vampire)

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
When the Dominators attempted to conquer Gallifrey, K9 fought alongside Leela against the invading Quarks which had "flooded" the Captiol, destroying 39 between them. (AUDIO: Time in Office)

Following an incident in the Death Zone, K9 accompanied Andred on a clean up in order to dispose of what creatures remained there. (AUDIO: Time in Office)

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 temporary destruction of Gallifrey in the War, 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)

K9 was with Leela on Gallifrey for many years, but it was only after the disappearance of her Time Lord husband, 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 delgates were part of the Free Time movement. He was able to get the codes to enter guarded parts of the platform with the helped 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 disarminant. He was asked by Romana to deactivate his other self to allow the bomb to detonate. (AUDIO: The Inquiry)

He accompanied Leela to catacombs of the Capitol and helped her come to terms with Andred's betrayal. When Leela went missing he contacted his other self 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)

After Leela became Romana's bodyguard, and after many important missions on her behalf, Leela's K9 was destroyed in a bomb explosion, leaving Leela heartbroken, but refusing to allow a duplicate unit to be built in its place. (AUDIO: Imperiatrix)

After being destroyed


K9 Mark I survived the explosion that Leela and Time Lord technology confirmed had utterly destroyed him.

At some point after this event, and indeed after the Last Great Time War, he 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)

Regeneration
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 K9. (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 came 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)

Personality
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.

Andred claimed "If [he] had a dog like [K9] in [his] unit, [he'd] make him a sergeant". (TV: The Invasion of Time)

The Doctor once described K9 as one of his best friends. (AUDIO: The Exxilons)

Features
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 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 (likely by the Time Lords or the Korven) so he could fly through the vacuum of space. (TV: Curse of Anubis)

K9 was capable of calculating 72 variables at once. (AUDIO: Requiem for the Rocket Men)

The Rocket Men installed a propulsion unit in K9 while he was in their possession. (AUDIO: Death Match)

K9 had a vast database inherited by his next incarnation containing data on the following aliens:
 * Glomb
 * Jixen
 * Meron
 * Mermaids of Gorgol XIII
 * Korven
 * Sporraxx
 * Oroborus
 * Medes
 * Aeolian
 * Yakoclaws

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."

- Bob Baker


 * 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.