The Fourth Doctor was played by English actor Tom Baker between 1974 and 1981. Baker’s Doctor was filled with wanderlust and a renewed curiosity towards exploring time and space.
This incarnation of the Doctor initially travelled with Sarah Jane Smith and Harry Sullivan, but Harry chose to remain on Earth when the opportunity arose. The Doctor and Sarah continued on their adventures until the Doctor was summoned to Gallifrey, necessitating that he leave Sarah Jane behind as humans were not allowed on Gallifrey.
After tangling with the Master on Gallifrey, he met and travelled with Leela of the Sevateem. During his travels with Leela, the Doctor gained a new companion in the robot dog, K9. Returning once more to Gallifrey to stop an invasion of Vardans, Leela and the original K9 stayed behind there.
On the White Guardian’s orders, the Doctor began looking for the Key to Time with fellow Time Lady Romana and K9 Mark II. Once that search was concluded, the Doctor and Romana went on the run from the Black Guardian. Not long after, Romana regenerated into a new body and continued to travel with the Doctor and K9. When they attempted to answer a Gallifreyan summons, the trio accidentally passed into the smaller universe of E-Space.
During his travels in E-Space, the Doctor gained a new companion in the teenaged mathematical genius Adric. Romana and K9 stayed behind in E-Space as the Doctor and Adric departed for N-Space. There, they encountered a Trakenite named Nyssa and a human named Tegan. The foursome successfully prevented the destruction of the universe by the Master, but only at the cost of this incarnation’s life.
Season 12 (1974-1975)
Season 13 (1975-1976)
Season 14 (1976-1977)
Season 15 (1977-1978)
Season 16 (1978-1979) – The Key to Time
Season 17 (1979-1980)
Season 18 (1980-1981)
The Doctor prepared for the worst when the Watcher, an entity born of his own immediate future, appeared to warn him of his demise. Due to the Master messing with the rotation controls for the Pharos radio telescope, the Doctor fell a great height. Suffering terrible injuries, he was assisted by the Watcher in his last moment, who joined with him and helped him regenerate into his next incarnation.
Followed by the Fifth Doctor.