Themes

Time travel

Same earth. Different point in time.

Straight-forward 'historicals' - stories that are set in the past, have no science fiction elements other than the presence of the Tardis, and that are to some extent meant to be educational:

• An unearthly child (1963)
• Marco Polo (1964)
• The Aztecs (1964)
• The Reign of Terror (1964)
• The crusade (1965)

Genre spoofs - stories that are in a genre that happens to be set in the past, rather than about actual history:

• The gunfighters (1966)
• Black orchid (1982)

(That's a bit of a stretch, really. 'The gunfighters' is an actual genre spoof, and the only thing setting it apart from the Robert Holmes genre bender is that there's no science fiction story lurking underneath. 'Black orchid' is a late 19th century gothic horror melodrama in an early 20th century setting that just happens to have the Tardis crew in it.)

Stories where time travel is part of the plot:

• The time meddler (1965)
• The time warrior (1973 - 1974)
• Time-flight (1982)
• Father's day (2005)
• The girl in the fireplace (2006)
• Blink (2007)
• The fires of Pompeii (2008)

Alternate futures:

• The enemy of the world (1967 - 1968)
• Utopia / The sound of drums / Last of the Time Lords (2007)
• Turn left (2008)

Space opera

To boldly go where no man has gone before.

• The Daleks (1963 - 1964)
• The keys of Marinus (1964)
• The Sensorites (1964)
• The web planet (1965)
• Galaxy 4 (1965)
• The tomb of the Cybermen (1967)
• The space pirates (1969)
• The ark in space (1975)
• The Sontaran experiment (1975)
• Genesis of the Daleks (1975)
• Planet of evil (1975)
• The robots of death (1977)
• Destiny of the Daleks (1979)
• The leisure hive (1980)
• The keeper of Traken (1981)
• Castrovalva (1982)
• The caves of Androzani (1984)
• Vengeance on Varos (1985)
• Timelash (1985)
• Revelation of the Daleks (1985)
• The end of the world (2005)
• New earth (2006)
• The impossible planet / The Satan pit (2006)
• Gridlock (2007)
• 42 (2007)
• Planet of the Ood (2008)
• The Doctor's daughter (2008)
• Silence in the library / Forest of the dead (2008)
• Midnight (2008)

Alien invasion

They're here...

• The Dalek invasion of earth (1964)
• The Daleks' master plan (1965 - 1966)
• The tenth planet (1966)
• The moonbase (1967)
• The faceless ones (1967)
• The evil of the Daleks (1967)
• The abominable snowmen (1967)
• The web of fear (1968)
• The wheel in space (1968)
• The invasion (1968)
• The seeds of death (1969)
• Spearhead from space (1970)
• The claws of Axos (1971)
• The hand of fear (1976)
• Logopolis (1981)
• The resurrection of the Daleks (1984)
• Remembrance of the Daleks (1988)
• The TV movie (1996)
• Rose (2005)
• Aliens of London / World war III (2005)
• Dalek (2005)
• The long game (2005)
• Boom town (2005)
• Bad wolf / The parting of the ways (2005)
• The Christmas invasion (2005)
• School reunion (2006)
• The idiot's latern (2006)
• Love and monsters (2006)
• Fear her (2006)
• Army of ghosts / Doomsday (2006)
• The runaway bride (2006)
• Smith and Jones (2007)
• Daleks in Manhattan / Evolution of the Daleks (2007)
• Partners in crime (2008)
• The Sontaran stratagem / The poison sky (2008)

Forbidden knowledge

Science and technology gone wrong.

• Planet of giants (1964)
• Inferno (1970)
• The green death (1973)
• Robot (1974 - 1975)
• Rise of the Cybermen / The age of steel (2006)
• The Lazarus experiment (2007)

Fantasy

What if...

• The edge of destruction (1964)
• The celestial toymaker (1966)
• The underwater menace (1967)
• The mind robber (1968)

Genre benders and history twisters

To me, these stories seem primarily idea-driven rather than plot-driven (though I realise this is a judgement call). Some appear to be one genre, but are actually something else; others provide alternative explanations for real historical events. The various writers who have worked on Doctor Who have come up with different versions of this general idea.

The Robert Holmes genre bender, a genre piece (usually a gothic horror tale) with a science-fiction story lurking underneath:

• Carnival of monsters (1973)
• Pyramids of Mars (1975)
• The talons of Weng-Chiang (1977)
• Horror of Fang Rock (1977)
• Ghost light (1989)
• The curse of Fenric (1989)
• The unquiet dead (2005)
• The empty child / The Doctor dances (2005)
• Tooth and claw (2006)
• The Shakespeare code (2007)
• Human nature / The family of blood (2007)
• Voyage of the damned (2007)
• The unicorn and the wasp (2008)

The Douglas Adams genre bender and history twister, a heist story which turns out to be a science fiction story, which, in turn, provides an alternative explanation for the existence of life on earth:

• City of death (1979)

The Eric Saward history twister. A science-fiction story that provides an alternative explanation for a historical event:

• The visitation (1982)
• Earthshock (1982)
• The mark of the Rani (1985)

Multiple-Doctor stories

Fan fun.

• The three Doctors (1972 - 1973)
• The five Doctors (1983)
• The two Doctors (1985)

Gallifrey stories

Stories set on the Doctor's home planet.

• Arc of infinity (1983)