A
- John Abbott
- Vince Hawkins, Horror of Fang Rock (1977)
- John Abineri
- Van Lutyens, Fury from the Deep (1968)
- General Carrington, The Ambassadors of Death (1970)
- Richard Railton, Death to the Daleks (1974)
- Ranquin, The Power of Kroll (1978–1979)
- John Acheson
- Major Beresford, The Seeds of Doom (1976)
- Christine Adams
- Cathica Kadanie, "The Long Game" (2005)
- Dallas Adams
- Howard Foster, Planet of Fire (1984)
- Tom Adams
- Vorshak, Warriors of the Deep (1984)
- Tony Adams
- Elgin, The Green Death (1973)
- Max Adrian
- King Priam, The Myth Makers (1965)
- Freema Agyeman
- Adeola Oshodi, "Army of Ghosts" (2006)
- Companion Martha Jones, "Smith and Jones" - "Last of the Time Lords" (2007), "The Sontaran Stratagem" - "The Doctor's Daughter", "The Stolen Earth" - "Journey's End" (2008), The End of Time (2010)
- Anthony Ainley
- Tremas, The Keeper of Traken (1981)
- The Master, The Keeper of Traken (1981) - Castrovalva (1982), Time-Flight (1982), The King's Demons (1983) - The Five Doctors (1983), Planet of Fire (1984) - The Caves of Androzani (1984), The Mark of the Rani (1985), The Trial of a Time Lord: The Ultimate Foe (1986), Survival (1989)
- Hajaz Akram
- Indian Newsreader, "Army of Ghosts" (2006)
- Sophie Aldred
- Ace, Dragonfire (1987) - Survival (1989)
- Terence Alexander
- Lord Ravensworth, The Mark of the Rani (1985)
- John Alkin
- Lomand, Planet of Fire (1984)
- Michael Allaby
- Ice Soldier / Larn, The Keys of Marinus (1964)
- Ronald Allen
- Rago, The Dominators (1968)
- Ralph Cornish, The Ambassadors of Death (1970)
- Bob Anderson
- Fighting Guard, The Enemy of the World (1968)
- Keith Anderson
- Robespierre, The Reign of Terror (1964)
- Adjoa Andoh
- Sister Jatt, "New Earth" (2006)
- Francine Jones, "Smith and Jones", "The Lazarus Experiment" - "42", "The Sound of Drums" - "Last of the Time Lords" (2007), "The Stolen Earth" - "Journey's End" (2008).
- Christien Anholt
- Perkins, The Curse of Fenric (1989)
- Bernard Archard
- Bragen, The Power of the Daleks (1966)
- Marcus Scarman, Pyramids of Mars (1975)
- Ben Aris
- Lieutenant Shears, Invasion of the Dinosaurs (1974)
- Ralph Arliss
- Tuar, Planet of the Spiders (1974)
- Gareth Armstrong
- Duke Guiliano, The Masque of Mandragora (1976)
- John Arnatt
- Chancellor Borusa, The Invasion of Time (1978)
- Max Arthur
- Zuko, Planet of Fire (1984)
- Daphne Ashbrook
- Companion Dr. Grace Holloway, Doctor Who (1996)
- Chloe Ashcroft
- Professor Laird, Resurrection of the Daleks (1984)
- Lyn Ashley
- Drahvin, Galaxy 4 (1965)
- David Ashton
- Kendron, Timelash (1985)
- Dicken Ashworth
- Sezon, Timelash (1985)
- Michael Attwell
- Isbur, The Ice Warriors (1967)
- Bates, Attack of the Cybermen (1985)
- John Atterbury
- Robot, The Mind Robber (1968)
- Alien Guard, The War Games (1969)
- Roger Avon
- Saphadin, The Crusade (1965)
- Daxtar, The Daleks' Master Plan (1965)
Read more about this topic: List Of Doctor Who Cast Members