Outer plasmic shell

The Doctor's TARDIS took the exterior form of a police box. (TV: An Unearthly Child)

An outer plasmic shell, often simply called a plasmic shell, was a TARDIS exterior.

Characteristics

In a perfectly functioning TARDIS, the chameleon circuit picked a plasmic shell suitable to the time and place in which the ship landed. A TARDIS's shells were stored in the shell room; if the room had no suitable shells, more were created and stored as well. (PROSE: The Little Things ^[+]Paul Beardsley, Short Trips: A Christmas Treasury (Short Trips short stories, 2004).) Lord Roche was forced to use a non-terrestrial aeroplane as his shell when he didn't have any terrestrial designs in his shell room and didn't feel like designing any. (PROSE: The Suns of Caresh ^[+]Paul Saint, BBC Past Doctor Adventures (BBC Books, 2002).) The theory in the TARDIS Handbook was that the plasmic shell was driven by the chameleon circuit. (TV: Logopolis ^[+]Christopher H. Bidmead, Doctor Who season 18 (BBC1, 1981).) When a TARDIS died or was dying, its final plasmic shell might grow to enormous size due to leakage of its dimensionally transcendental interior. (TV: The Name of the Doctor ^[+]Steven Moffat, Doctor Who series 7 (BBC One, 2013).)

The Second Doctor boasted that the TARDIS was made from the "hardest materials in existence", making it near impervious to harm. (COMIC: The Monsters from the Past ^[+]Roger Noel Cook, TVC comic stories (1967).) Indeed, firepower from Dalek gunsticks were unable to penetrate the plasmic shell. (AUDIO: Beneath the Viscoid ^[+]Nicholas Briggs, Only the Good (The War Master, Big Finish Productions, 2017).)

The Tremas Master used his chameleon circuit to bond his TARDIS' plasmic shell with the Third Doctor's. (PROSE: The Quantum Archangel ^[+]Craig Hinton, BBC Past Doctor Adventures (BBC Books, 2001).)

Later, more sentient TARDISes could decide what to change into all by themselves. (PROSE: Alien Bodies ^[+]Lawrence Miles, BBC Eighth Doctor Adventures (BBC Books, 1997).)

When the Doctor's TARDIS entered siege mode, its exterior took the shape of a cube etched with Gallifreyan writing. (TV: Flatline ^[+]Jamie Mathieson, Doctor Who series 8 (BBC One, 2014).)

The Doctor's TARDIS

Among plasmic shells used by the Doctor's Type 40 TARDIS were: a boulder, (AUDIO: The Beginning ^[+]Error: Code 2 - no data stored in variables, cache or SMW., PROSE: Frayed ^[+]Tara Samms, Telos Doctor Who novellas (Telos Publishing, 2003).) an Ionic column and a sedan chair, (TV: An Unearthly Child ^[+]Anthony Coburn, adapted from The Pilot Episode (Anthony Coburn), Doctor Who season 1 (BBC tv, 1963).) a wooden kiosk, (AUDIO: Quinnis ^[+]Marc Platt, The Companion Chronicles (2010).) a shed (PROSE: The Price of Conviction ^[+]Error: Code 2 - no data stored in variables, cache or SMW.) and a post box. (PROSE: The Little Things ^[+]Paul Beardsley, Short Trips: A Christmas Treasury (Short Trips short stories, 2004).) However due to a malfunction in the chameleon circuit, caused by the Eleventh Doctor, (COMIC: Hunters of the Burning Stone ^[+]Scott Gray, DWM Comics (2013).) the Doctor's TARDIS became stuck with a police box plasmic shell after leaving 1963 London. (TV: An Unearthly Child ^[+]Anthony Coburn, adapted from The Pilot Episode (Anthony Coburn), Doctor Who season 1 (BBC tv, 1963).)

Whilst the ship was infected by Scratchman, vines grew through the windows of the exterior and wrapped themselves around the outer shell, causing the police assistance sign to fall off. (PROSE: Scratchman ^[+]Tom Baker and James Goss, adapted from Doctor Who Meets Scratchman, BBC Books novelisations (BBC Books, 2019).)

The shell of the Doctor's TARDIS had deteriorated by the time Romana I travelled with the Doctor. After a near miss by a missile in Atrios orbit, (TV: The Armageddon Factor ^[+]Bob Baker and Dave Martin, Doctor Who season 16 (BBC1, 1979).) she designed a routine to strengthen it, though the Doctor disabled it as he abhorred tampering. He regretted the action when a missile was aimed at the TARDIS in Proxima Major orbit. (AUDIO: The Dalek Contract ^[+]Error: Code 2 - no data stored in variables, cache or SMW.)

For a short period of time, the Sixth Doctor managed to repair the chameleon circuit, resulting in the outer shell taking the appearance of a stove, an organ and a doorway. The shell eventually returned to the shape of a police box. (TV: Attack of the Cybermen ^[+]Paula Moore, Doctor Who season 22 (BBC1, 1985).)

In 1854, the TARDIS was struck by cannon fire which displaced the outer shell. This triggered the Hostile Action Displacement System, causing the TARDIS to retreat to the Time Vortex where it grew a new shell. The new shell was still a police box, but was coloured white. The remains of the old shell were used as fire wood by soldiers. (AUDIO: The Angel of Scutari ^[+]Paul Sutton, Main Range (Big Finish Productions, 2009).) The outer shell later regained its normal blue colour. (AUDIO: Black and White ^[+]Matt Fitton, Main Range (Big Finish Productions, 2012).)

During the Last Great Time War, the TARDIS’ outer shell showed signs of wear and tear. (TV: The Night of the Doctor ^[+]Steven Moffat, Doctor Who 50th Anniversary Specials minisode (BBC One, 2013)., The Day of the Doctor ^[+]Steven Moffat, 50th Anniversary Specials (BBC One, 2013).)

By the time of the Tenth Doctor, the outer shell appeared to have deviated somewhat from the original design of a police box as DCI Billy Shipton noted that its windows were the wrong size. (TV: Blink ^[+]Steven Moffat, adapted from What I Did on My Christmas Holidays by Sally Sparrow (Steven Moffat), Doctor Who series 3 (BBC One, 2007).)

Whilst honing in on the Tenth Doctor whilst he was trapped by the Trickster, the TARDIS covered the outer shell in artron energy to fight the Trickster’s power. Clyde Langer was infused with the energy after he made contact with the outer shell whilst trying to board the ship. (TV: The Wedding of Sarah Jane Smith ^[+]Gareth Roberts, The Sarah Jane Adventures series 3 (BBC One, 2009).)

Whilst confronting the Prometheans, the Eleventh Doctor learnt that the police box shape of the TARDIS’ outer shell had become part of humanity’s race memory due to his many visits to Earth, even speculating it had paradoxically influenced the design of police boxes in the first place. He used this to his advantage to free humanity from the Prometheans’ control. (COMIC: Hunters of the Burning Stone ^[+]Scott Gray, DWM Comics (2013).)

In an alternate timeline, the TARDIS' outer shell retained the police box shape up through its final resting place as the Doctor's tomb on Trenzalore, though it grew to an enormous size due to size leakage. (TV: The Name of the Doctor ^[+]Steven Moffat, Doctor Who series 7 (BBC One, 2013).)

When the TARDIS' power was drained by the Boneless, the outer shell shrank, causing the Twelfth Doctor to be trapped inside. It became small enough that Clara Oswald was able to fit it in her handbag. After she tricked the Boneless into returning power to the TARDIS, the outer shell regained its usual size. (TV: Flatline ^[+]Jamie Mathieson, Doctor Who series 8 (BBC One, 2014).)

When the TARDIS crash landed on Earth in the Crimean War after an encounter with the Flux, the door disappeared from the outer shell, preventing access to the interior. Trying to re-enter her ship, the Thirteenth Doctor found only windows on each side of the police box exterior. (TV: War of the Sontarans ^[+]Chris Chibnall, Doctor Who series 13 (BBC One and BBC America, 2021).)

When the TARDIS created a time loop to save the Doctor and her companions from extermination by Dalek Executioners, the outer shell became covered in red cracks. After the loop ended when the Doctor destroyed the Daleks, the TARDIS' appearance returned to normal. (TV: Eve of the Daleks ^[+]Chris Chibnall, Doctor Who New Year Special 2022 (BBC One, 2022).)