Doctor Who — Season 15
This season introduced K9 to the series and saw the departure of Leela. It was originally intended to include Terrance Dicks' story The Vampire Mutations but, due to a major BBC production of Dracula, it was postponed. It later became Season 18's State of Decay. To replace it, Dicks quickly scripted the season opener, Horror of Fang Rock. The season took a two week transmission break over the 1977 Christmas period, between the broadcast of part four of The Sun Makers and part one of Underworld.
Episodes

E01 Horror of Fang Rock (1)
★ 7.8Sep 3, 1977 · 25m
The English channel, the 1900s AD. The TARDIS lands on barren Fang Rock, inhabited until now only by three lighthouse keepers. But what is the strange fog covering the island, and can it be connected to the falling star sighted earlier that night?

E02 Horror of Fang Rock (2)
★ 7.6Sep 10, 1977 · 25m
The survivors of a wrecked ship are stranded with the lighhouse crew on Fang Rock as a deadly menace slithers through the fog. Has the Beast of Fang Rock returned?

E03 Horror of Fang Rock (3)
★ 7.5Sep 17, 1977 · 25m
The Doctor barricades everyone in the lighthouse to protect them from the mysterious deadly creature in the fog. But it may already be inside, biding its time…

E04 Horror of Fang Rock (4)
★ 7.6Sep 24, 1977 · 25m
The Rutan starts picking off the surviving humans one by one as the Doctor and Leela struggle to defeat not only the alien but an entire fleet waiting to occupy Earth.

E05 The Invisible Enemy (1)
★ 6.9Oct 1, 1977 · 25m
Deep space, 5000AD. An Earth supply shuttle is infected by a strange sentient space-borne virus, which quickly spreads to the crew of the refuelling station on the moon Titan. Even worse, the Doctor himself falls victim. But why is Leela immune, and what is the virus's ultimate goal?

E06 The Invisible Enemy (2)
★ 7.0Oct 8, 1977 · 25m
Leela and Lowe take the Doctor to the Bi-Al Foundation for help. But how can they cure an infection of the mind?

E07 The Invisible Enemy (3)
★ 7.3Oct 15, 1977 · 25m
Miniaturised clones of the Doctor and Leela are injected into his brain. But they must now fight the virus on its own level. And its servants are closing in around them.

E08 The Invisible Enemy (4)
★ 7.1Oct 22, 1977 · 25m
The Nucleus, now grown to human size, is determined to spawn and take over the Galaxy. Only the Doctor and Leela can stop it.

E09 Image of the Fendahl (1)
★ 6.6Oct 29, 1977 · 25m
England, the late 1970s. At Fetch Priory, Dr Fendelman's experiments with the new Time Scanner are disrupted by the mysterious death of a hiker, nearby. Then there's the mysterious skull, also being used as part of his work. A skull that seems to predate the evolution of mankind. What is the true role of the Fendahl in humanity's evolution?

E10 Image of the Fendahl (2)
★ 6.5Nov 5, 1977 · 25m
The mystery surrounding the strange skull deepens. Thea is slowly succumbing to its influence while the Doctor prepares to battle a creature from mythology.

E11 Image of the Fendahl (3)
★ 6.8Nov 12, 1977 · 25m
While Max prepares to tap supernatural forces beyond imagining, the Doctor and Leela investigate the legend of the Fendahl.

E12 Image of the Fendahl (4)
★ 6.7Nov 19, 1977 · 25m
The Fendahl is returning to life, ready to consume everything in its path. Can the Doctor find a way to kill death itself?

E13 The Sun Makers (1)
★ 6.9Nov 26, 1977 · 25m
Pluto, the distant future. The planet has been terraformed and is now orbited by artificial suns, provided by the rapacious company who ruthlessly exploit the relocated human workforce. The Doctor, Leela, and K9 arrive and befriend a luckless drone worker, but they must flee with him to the dark undercity...

E14 The Sun Makers (2)
★ 7.0Dec 3, 1977 · 25m
The Doctor has been captured by the Gatherer. Leela works to free him but the Gatherer is already laying his own plans…

E15 The Sun Makers (3)
★ 7.3Dec 10, 1977 · 25m
Now Leela is the prisoner of the Collector. He knows of the Doctor and is determined to rid himself of both of them.

E16 The Sun Makers (4)
★ 7.0Dec 17, 1977 · 25m
The Doctor now moves to completely overthrow the Company. But the Collector has one last trump card to play.

E17 Underworld (1)
★ 6.0Jan 7, 1978 · 25m
Deep space, an unknown time. The Doctor encounters the Minyans, survivors of a race the Time Lords unwittingly obliterated early in their own history. The Minyans are searching for their race's lost gene banks, a quest which takes them to the edge of the galaxy…

E18 Underworld (2)
★ 6.0Jan 14, 1978 · 25m
After 100,000 years, the Minyans have found the long-lost P7E. But what awaits them on the ship, long buried in the core of a newborn planet?

E19 Underworld (3)
★ 6.0Jan 21, 1978 · 25m
The Minyans have, at long last, found the P7E. But a host of guards and robotic seers stand between them and the race banks.

E20 Underworld (4)
★ 6.3Jan 28, 1978 · 25m
The Minyons struggle to gain the precious race banks from the Oracle. But perhaps it is giving in a little too easily ...

E21 The Invasion of Time (1)
★ 7.3Feb 4, 1978 · 25m
Gallifrey, world of the Time Lords. The Doctor returns and claims the vacant presidency. But his behaviour is erratic and his motives mysterious.

E22 The Invasion of Time (2)
★ 7.1Feb 11, 1978 · 25m
The Doctor is made president of the Time Lords. He immediately orders K-9 to lower the planet's defences and has Leela banished to the wilderness.

E23 The Invasion of Time (3)
★ 6.6Feb 18, 1978 · 25m
The Doctor has betrayed his own people and enabled a Vardan invasion of Gallifrey. Leela joins forces with the Outsiders and prepares to strike back against the aliens.

E24 The Invasion of Time (4)
★ 6.6Feb 25, 1978 · 25m
The Doctor works to free his planet of the Vardan menace. How can he defeat an enemy who can read his very thoughts? And does their invasion conceal a greater menace?

E25 The Invasion of Time (5)
★ 7.1Mar 4, 1978 · 25m
The Sontarans have invaded Gallifrey, seeking to seize the incredible power of the Time Lords. The Doctor's first step is to cut them off from their fleet. But Kelner is helping the enemy…

E26 The Invasion of Time (6)
★ 6.9Mar 11, 1978 · 25m
The Sontarans finally invade the TARDIS itself, seeking the Great Key. The Doctor, however, has other uses for this powerful object…
Other Seasons
EPS42Season 11963
EPS39Season 21964
EPS45Season 31965
EPS43Season 41966
EPS40Season 51967
EPS44Season 61968
EPS25Season 71970
EPS25Season 81971
EPS26Season 91972
EPS26Season 101972
EPS26Season 111973
EPS20Season 121974
EPS26Season 131975
EPS26Season 141976
EPS26The Key to Time1978
EPS20Season 171979
EPS28Season 181980
EPS26Season 191982
EPS22Season 201983
EPS24Season 211984
EPS13Season 221985
EPS14The Trial of a Time Lord1986
EPS14Season 241987
EPS14Season 251988
EPS14Season 261989