The Fourth Doctor
Portrayed by: Tom Baker
Years active: 1974 - 1981
Series: Classic
Companions: Sarah Jane Smith, Harry Sullivan, Leela, K-9 (Mark I and II), Romana (I and II), Adric, Tegan Jovanka, Nyssa of Traken
Following radiation poisoning in the Great One's lair on Metebelis III, the Doctor regenerated into the Fourth Doctor, who appeared to be in a hurry to leave Earth, though he was convinced by Brigadier Lethbridge-Stewart to stay and assist him with the Think Tank and their K1 Robot, before taking both Sarah Jane Smith and Harry Sullivan as his companions on his travels. The Fourth Doctor, along with Sarah Jane and Harry, were enlisted by the Time Lords to try and prevent the creation of the Daleks in Genesis of the Daleks (Classic Series). However, the Doctor showed compassion to the Daleks and refused to stop their creation, even though he knew he was sentencing millions of people in the future to death by the Daleks, he also knew that they were part of the universe enough that they needed to be around. Instead he merely hindered their creation, causing them to be 1000 years late in development than they previously would have done. This act is thought to have caused the Time War between the Time Lords and the Daleks that resulted in the loss of Gallifrey and the Time Lords. Despite his hurry to leave Earth, the Fourth Doctor did return to defeat the Zygons in Terror of the Zygons (Classic Series) where Harry opted to leave the TARDIS crew and remain on Earth. Though the Doctor did intend to resign from UNIT as their unpaid scientific advisor, he never got round to doing so and remained on their staff list despite leaving them in Pyramids of Mars (Classic Series). After numerous adventures with Sarah Jane, the Fourth Doctor was called to Gallifrey through telepathic summons and chose to return Sarah Jane to Earth. He intended to leave her near her home in South Croydon in The Hand of Fear (Classic Series), though it was revealed in School Reunion (Series 2 : Episode 3) that he had in fact left her in Aberdeen.
On Gallifrey, the Fourth Doctor defeated the Master and renewed his acquaintance with a former teacher of his, Borusa, as well as re-experiencing, much to his disgust, the decadence of Time Lord civilisation in The Deadly Assassin (Classic Series). After this, the Doctor travelled to a nameless jungle world where he picked up new companion, Leela, a girl of the Sevateem in The Face of Evil (Classic Series). Together the pair fixed the human colony ship's powerful computer, Xoanon, and met the magician Li Hsien Chang in Victorian Longon in The Tallons of Weng-Chiang (Classic Series), as well as visiting the Bi-Al Foundation medical centre where they picked up the Mark I version of the robot dog, K9 in The Invisible Enemy (Classic Series). Later, posing as a power-mad and vainglorious man, the Fourth Doctor returned to Gallifrey with the intent of attaining the office of Lord President. However, this was merely a scheme to save his home world from the invasion of the Sontarans and the Vardans. After this successful mission, Leela chose to remain on Gallifrey with Andred, a Gallifreyan in the Chancellory Guard, and K9, though the Doctor managed to leave the Capitol with a Mark II K9 in a crate in The Invasion of Time (Classic Series).
Following his mission on Gallifrey, the Doctor was summoned by the White Guardian, who gave him the quest to locate and assemble the segments that made the Key to Time. For this quest, the White Guardian also bestowed upon the Doctor his new companion, Romana, a fellow Time Lord, marking the first return of a second Time Lord companion since Susan Foreman had left the TARDIS crew with the First Doctor. The Fourth Doctor and Romana successfully located, assembled and disassembled the Key to Time, though the Doctor added a randomiser in the TARDIS to escape the wrath of the Black Guardian, the opposite of the White Guardian in The Armageddon Factor (Classic Series). Later, in Destiny of the Daleks (Classic Series), despite finishing the quest, the Doctor continued to travel with Romana and K9 as his companions, even after Romana's regeneration. After some time travelling with Romana and K9, the Doctor became trapped in E-Space, a pocket universe in Full Circle (Classic Series), where he picked up a new companion, Adric. After finding a way to leave the pocket universe, Romana and K9 opted to stay behind. Romana's departure from the TARDIS brought a dark mood upon the Fourth Doctor that stayed with him for the remainder of his incarnation. During a final battle with the Master in Logopolis (Classic Series) the Doctor acquired two new companions, Tegan Jovanka and Nyssa of Traken.
Of all the Doctors incarnations thus far, the Fourth Doctor was the least human-like in his nature, even standing out from his own people with his personality. Occasionally the Fourth Doctor appeared callous, which Sarah Jane would pull him up for, though he would remind her that they had bigger problems than whatever he was being callous over. Much like his Second incarnation, the Fourth Doctor liked to keep his friends and enemies off guard with oddball humour, and leaping ahead in ideas, sometimes ahead of himself. As with most of his incarnations, the Fourth Doctor was gentle, though was not against striking out if necessary, or even taking a life in extreme circumstances, though he did scold Leela for unnecessary killing in The Face of Evil. The Fourth Doctor refused to help those who had brought bad deeds onto themselves, such as the mutating Sorenson, who's experiment results were his own fault, though once the process had been reversed the Fourth Doctor did then assist Sorenson. The Fourth Doctor was also an excellent judge of character, knowing very quickly, almost instantly, who to trust and who not to, though of all the Doctor's incarnations, the Fourth Doctor was perhaps the one with the most consistent of anti-authoritarian attitude, even having little tolerance for nationalism or religious dogma. Despite his charm and offbeat humour however, the Fourth Doctor was the most aloof and sombre out of the first four Doctors. He could often be intensely brooding and serious as well as callous, keenly scrutinising his surroundings and the people around him, even if he was playing a fool to make people underestimate him. Although the Time Lords lifted his exile, the Fourth Doctor still kept his distance from them, almost preferring a more solitary life, though he always got annoyed that the Time Lords could enter his life at their choosing when they deemed it necessary to do so. As well as distancing himself from the Time Lords, the Fourth Doctor also attempted to distance himself from humanity, though he did state that mankind was his favourite species.
The Fourth Doctor was the first incarnation following the Third Doctor to try and break his ties to UNIT, and reacted with anger when they recalled him to Earth in Terror of the Zygons. Other than that, and a few other occasions, the Fourth Doctor kept his distance from UNIT, even sacrificing the Third Doctor's roadster, Bessie. Following incarnations would also keep their distance from UNIT, though the Ninth and Tenth incarnations would assist UNIT when called in to help. Being the youngest looking incarnation of the Doctor thus far, he was found to be drawn closer to his companions than other Doctors, though he never appeared to notice.
In a very stark contrast to the Third Doctor's elegant dress, the Fourth Doctor dressed somewhat flamboyantly, in an unkempt and awkward-looking figure, becoming famous for wearing a ridiculously long multi-coloured scarf, and occasionally a large floppy hat. Though the Doctor's clothes changed multiple times throughout his incarnation, the scarf usually remained in some form, knitted for him by Madame Nostradamus in The Ark in Space (Classic Series). His coat included dimensionally transcendental pockets, capable of holding many items which included a seemingly endless supply of jelly babies, the Fourth Doctor's favourite, as well as a cricket ball, a yo-yo, used for taking gravity readings, a selection of books including his 500 year diary, a galactic passport and many other items. On one occasion the Fourth Doctor also dropped a cup of hot drink into his pocket in The Power of Kroll (Classic Series).
The Fourth Doctor inspired later incarnation's fear of heights and climbing high items, following a fall during battle with the Master in Logopolis. While struggling with the Master, the Fourth Doctor fell from the Pharos Project radio telescope to the ground, hundreds of feet below him. However, the Doctor was not surprised at his regeneration, revealing that a mysterious entity known as the Watcher had been following him, which he took to mean his regeneration was nigh. The Watcher that had been tracking the Fourth Doctor through time and space then merged with him, and the Fourth Doctor regenerated into his next incarnation, the Fifth Doctor.