Season 21

Season 21 of Doctor Who ran between 5 January 1984 and 30 March 1984. It starred Peter Davison as the Fifth Doctor. The last story, The Twin Dilemma, introduced Colin Baker as the Sixth Doctor.

Overview
The season consisted of seven serials and twenty-four episodes. The Twin Dilemma, the first story with Colin Baker as the Sixth Doctor, aired last in the season. This season saw the departure of companions Tegan, Turlough and Kamelion and introduced Peri. Most episodes were the traditional twenty-five minute length. However, due to coverage of the 1984 Winter Olympics, Resurrection of the Daleks was re-edited before airing and shown as two forty-five minute episodes.

Colin Baker's first story, The Twin Dilemma, introduced a modified version of the opening credits including a slight modification to the series logo (although the theme arrangement was not changed). This was the first time since Season 4 that such a change occurred during a season.

Along with Season 4, it was one of only two seasons of the classic series to have a completely different cast in the final story of the season than in the first story.

Recurring

 * The Fifth Doctor - Peter Davison (up to The Caves of Androzani)
 * Tegan Jovanka - Janet Fielding (up to Resurrection of the Daleks)
 * Vislor Turlough - Mark Strickson (up to Planet of Fire)
 * Peri Brown - Nicola Bryant (from Planet of Fire onwards)
 * The Sixth Doctor - Colin Baker (from The Caves of Androzani onwards)
 * Davros - Terry Molloy
 * Lytton - Maurice Colbourne
 * Kamelion (voice) - Gerald Flood
 * - Anthony Ainley

Guest

 * Solow - Ingrid Pitt
 * Vorshak - Tom Adams
 * Bulic - Nigel Humphreys
 * Jane Hampden - Polly James
 * Sir George Hutchinson - Denis Lill
 * Colonel Wolsey - Glyn Houston
 * Joseph Willow - Jack Galloway
 * Will Chandler - Keith Jayne
 * Andrew Verney - Frederick Hall
 * Brazen - Peter Gilmore
 * Norna - Lesley Dunlop
 * Range - William Lucas
 * Plantagenet - Jeff Rawle
 * Cockerill - Maurice O'Connell
 * Stien - Rodney Bewes
 * Professor Howard Foster - Dallas Adams
 * Timanov - Peter Wyngarde
 * Sharaz Jek - Christopher Gable
 * Morgus - John Normington
 * Salateen - Robert Glenister
 * Stotz - Maurice Roëves
 * Professor Edgworth / Azmael - Maurice Denham
 * Mestor - Edwin Richfield

Stories set during this season

 * PROSE: Deep Blue (between Warriors of the Deep and The Awakening)
 * PROSE: The King of Terror (between The Awakening and Frontios)
 * PROSE: Lords of the Storm (between Resurrection of the Daleks and Planet of Fire)
 * AUDIO: Phantasmagoria (between Resurrection of the Daleks and Planet of Fire)
 * AUDIO: Loups-Garoux (between Resurrection of the Daleks and Planet of Fire)
 * AUDIO: Singularity (between Resurrection of the Daleks and Planet of Fire)
 * PROSE: Imperial Moon (between Resurrection of the Daleks and Planet of Fire)
 * AUDIO: Red Dawn (between Planet of Fire and The Caves of Androzani)
 * PROSE: The Ultimate Treasure (between Planet of Fire and The Caves of Androzani)
 * PROSE: Superior Beings (between Planet of Fire and The Caves of Androzani)
 * PROSE: Warmonger (directly after Superior Beings)
 * AUDIO: Exotron (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Urban Myths (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Eye of the Scorpion (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Church and the Crown (between Planet of Fire and The Caves of Androzani)
 * AUDIO: No Place Like Home (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Nekromanteia (between Planet of Fire and The Caves of Androzani)
 * PROSE: Blood and Hope (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Axis of Insanity (between Planet of Fire and The Caves of Androzani)
 * PROSE: Graham Dilley Saves the World (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Roof of the World (between Planet of Fire and The Caves of Androzani)
 * PROSE: The Gangster's Story (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Three's a Crowd (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Council of Nicaea (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Kingmaker (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Veiled Leopard (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Gathering (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Cuddlesome (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Mind's Eye (between Planet of Fire and The Caves of Androzani)
 * PROSE: Far Away in a Manger (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The 100 Days of the Doctor (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Bride of Peladon (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Mission of the Viyrans (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Judgement of Isskar (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Destroyer of Delight (between Planet of Fire and The Caves of Androzani)
 * AUDIO: The Chaos Pool (between Planet of Fire and The Caves of Androzani)
 * AUDIO: Peri and the Piscon Paradox (immediately before The Caves of Androzani)
 * AUDIO: Winter (during The Caves of Androzani)

VHS

 * Warriors of the Deep (1995)
 * The Awakening/Frontios (1997)
 * Resurrection of the Daleks (1993/2001)
 * Planet of Fire (1998)
 * The Caves of Androzani (1992)
 * The Twin Dilemma (1992)

DVDs
All serials of season 21 were released individually in between 2001 and 2011.

Novels

 * Warriors of the Deep
 * The Awakening
 * Frontios
 * Planet of Fire
 * The Caves of Androzani
 * The Twin Dilemma

Target Books was unable to come to an agreement that would have allowed Resurrection of the Daleks to be adapted as a novel; it remains one of a handful of classic-era stories not to be novelised.