Theory:Timeline - Third Doctor

This page lists appearances of the Third Doctor in the order in which he experienced them. This timeline is based upon observations of the Doctor Who universe and the events that occur during each of these stories. From these observations we have attempted to build a concise timeline. It is assumed, much like its TV story counterparts that for each novel or audio series their published/numbered order is the order they occur in. This does not apply to short stories which are often ambiguous about their placement. There are also many gaps between stories.

The layout of this timeline is in part based on the observations on Doctor Who Reference Guide and Doctor Who - The Complete Adventures, as well as Lance Parkin's AHistory and other sources that allow us to make observations, such as DocOhoReviews, The History of Doctor Who, The Discontinuity Guide, Clive Banks Databank, Big Finish forums, The Whoniverse and The Divergent Universe forums. None of these sources should be used solely as a source or considered a "true" timeline for stories.

Additionally there are statements on the back of Virgin Missing Adventures and many BBC Past Doctor Adventures novels that state between which TV stories the novel takes place between. These can be used to narrow the field, and should be viewed as the only placing for these novels.

Limiting factors
Any stories involving the Doctor travelling around several destinations in his TARDIS should take place following TV: The Three Doctors, prior to this he is limited to travels "on assignment" for the Time Lords. Any limited trip with Jo Grant must take place after TV: Colony in Space. Any story where he is not on assignment but travelling freely with Jo must take place after TV: The Three Doctors and before TV: The Green Death. Any story with Sarah Jane Smith must take place after TV: The Time Warrior and before TV: Planet of the Spiders.

UNIT career begins

 * TV: Spearhead from Space
 * The Doctor has regenerated from his previous incarnation. Upon recovering, he assists UNIT in combating the Nestene Consciousness's Auton invasion and is asked by Brigadier Alistair Gordon Lethbridge-Stewart to become UNIT's scientific advisor with Dr. Liz Shaw, and he accepts in return for a car.


 * PROSE: Caught in the Web
 * Liz is examining the leftovers of the Auton invasion.


 * COMIC: The Arkwood Experiments
 * COMIC: The Multi-Mobile
 * COMIC: Insect
 * AUDIO: Vengeance of the Stones
 * The Doctor has had Bessie for a relatively short period of time.


 * COMIC: The Metal Eaters
 * PROSE: Invaders Invisible
 * Before this point, the Doctor had not had an adventure without the Brigadier since his exile to Earth.


 * COMIC: Assassin from Space
 * COMIC: Undercover
 * TV: Doctor Who and the Silurians
 * The Doctor encounters the Silurians for the first time, but, to his dismay, they are killed and their city destroyed on the Brigadier's orders.

After the Wenley Moor massacre

 * PROSE: The Straw that Broke the Camel's Back
 * The outcome of Doctor Who and the Silurians is still fresh on the Doctor's mind.


 * AUDIO: Old Soldiers
 * Set a few weeks after Doctor Who and the Silurians.


 * AUDIO: Shadow of the Past
 * The Doctor is still unhappy about the outcome of Doctor Who and the Silurians.


 * TV: The Ambassadors of Death
 * The Doctor has yet to forgive the Brigadier for the outcome of Doctor Who and the Silurians. Corporal Benton has only recently been promoted to Sergeant.

Christmas]]''
 * PROSE: The Mind Extractors
 * PROSE: The Ghouls of Grestonspey
 * PROSE: The Dark Planet
 * PROSE: Caverns of Horror
 * PROSE: A Universe Called Fred
 * PROSE: ''[[UNIT Christmas Parties: First Christmas (short story)|UNIT Christmas Parties: First
 * Liz has been working with UNIT for "a few months", and her complaints about her job here are similar to those that the Brigadier cites as her reason for leaving. The TARDIS console has also been removed from within the ship, as it was in The Ambassadors of Death.


 * AUDIO: Walls of Confinement
 * This is the second time the Doctor has visited a zoo, setting this after The Arkwood Experiments.


 * AUDIO: A Home From Home
 * PROSE: Prelude White Darkness
 * The Brigadier finds it doubtful that the Doctor can get the TARDIS to work, setting this before Inferno.


 * PROSE: Soldiers from Zolta
 * It is summer.


 * AUDIO: The Last Post
 * Concludes shortly before Inferno.


 * TV: Inferno
 * PROSE: Still Lives
 * Set immediately after Inferno.


 * COMIC: The Fishmen of Carpantha
 * COMIC: Doctor Who and the Rocks from Venus
 * AUDIO: The Blame Game
 * It has been "months" since Spearhead from Space, and the Monk also mentions the events of  Doctor Who and the Silurians. Liz has heard the Doctor's TARDIS materialise before, placing this after Inferno.


 * PROSE: The Science of Magic
 * PROSE: The Eye of the Giant
 * Mike Yates arrives at UNIT and sees inside the TARDIS for the first time, and the Doctor mentions visiting the parallel universe from Inferno.


 * PROSE: Hiccup in Time
 * One of the Doctor's attempts to repair the TARDIS sends Liz back in time to 1539.

Liz resigns

 * AUDIO: The Blue Tooth
 * Liz decides to leave UNIT.


 * AUDIO: Binary
 * Liz announces her intentions to leave UNIT.


 * PROSE: The Scales of Injustice
 * Liz officially leaves UNIT, Yates is promoted to Captain Rank, and the Doctor is in a new laboratory.


 * PROSE: Prisoners of the Sun
 * Liz has just recently left UNIT.


 * AUDIO: The Rings of Ikiria
 * Set after Doctor Who and the Silurians.


 * COMIC: Castaway
 * COMIC: Levitation
 * PROSE: Danse Macabre
 * With no travelling companion, the Doctor meets Horatio Nelson, whom he refers to as a good friend in The Sea Devils.


 * COMIC: Doctor Who and the Robot
 * COMIC: Trial of Fire
 * COMIC: The Kingdom Builders
 * PROSE: The Devil Goblins from Neptune
 * Liz is called back to UNIT, and has been absent long enough for the Doctor to admit missing her company.


 * PROSE: Reconnaissance
 * The Master is at large, setting this after Prisoners of the Sun.


 * PROSE: Country of the Blind
 * Liz has decided to tell the Doctor about her decision to officially leave UNIT, placing it after Prisoner of the Sun where the Doctor finds out from the Brigadier.

Battles with the Master

 * TV: Terror of the Autons
 * Jo Grant joins UNIT as the Doctor's new assistant, just in time for UNIT's first battle with.


 * AUDIO: The Sentinels of the New Dawn
 * Months have passed for Liz since she left UNIT, and the Doctor now has a new assistant, placing this after Terror of the Autons.


 * AUDIO: The Doll of Death
 * Though the audio's blurb places it between The Dæmons and Day of the Daleks, Jo is still quite new to UNIT, and is unaware of the true nature of the TARDIS, setting it before The Claws of Axos.


 * PROSE: Dark Intruders
 * PROSE: War in the Abyss
 * PROSE: Hunt to the Death
 * PROSE: Doorway into Nowhere
 * The Master is also trapped on Earth, setting this before The Mind of Evil.


 * PROSE: The Claw
 * PROSE: Saucer of Fate
 * PROSE: The Phaser Aliens
 * AUDIO: Damascus
 * TV: The Mind of Evil
 * AUDIO: The Mega
 * The Mega received advice from the Master, setting this after he got his TARDIS working in The Mind of Evil.


 * PROSE: Deadly Reunion
 * The Master has a working TARDIS, placing this after The Mind of Evil.


 * PROSE: Angel
 * The Doctor is visibly chafing at his confinement to 20th century Earth.

Christmas Truce]]''
 * PROSE: A Visit to the Cinema
 * PROSE: ''[[UNIT Christmas Parties: Christmas Truce (short story)|UNIT Christmas Parties:
 * The Doctor hasn't seen the Master since Deadly Reunion.


 * TV: The Claws of Axos
 * From a deal with the Master, the Doctor is able to restore his TARDIS back to working order, only to discover the Time Lords have programmed it to always return him to 20th century Earth.


 * PROSE: The Thousand Years of Christmas
 * The Doctor has just discovered that even if he can now depart with the TARDIS, he will be drawn back to Earth, setting this after The Claws of Axos.


 * COMIC: Change of Mind
 * PROSE: The Tip of the Mind
 * The Doctor incorrectly believes that the Time Lords have lifted his exile.


 * TV: Colony in Space
 * Jo Grant's first visit to another planet.


 * TV: The Dæmons
 * After his failed escape attempt upon his defeat, the Master is arrested by UNIT.


 * AUDIO: Degrees of Truth
 * Set immediately after The Dæmons.


 * PROSE: Freedom
 * Set after the Master's arrest in The Dæmons.


 * COMIC: Gemini Plan
 * COMIC: Timebenders
 * COMIC: The Forgotten: Renewal
 * PROSE: The Thing from Outer Space
 * PROSE: Harvest of Time
 * Set between The Dæmons and The Sea Devils, as the Master is still in prison.


 * AUDIO: The Magician's Oath
 * Set between The Dæmons and Day of the Daleks.


 * COMIC: The Man in the Ion Mask
 * Set sometime after The Dæmons, and no long before The Face of the Enemy.

Missions in time

 * TV: Day of the Daleks
 * COMIC: Time & Time Again
 * Set during Day of the Daleks: Episode 1.


 * PROSE: Who Killed Kennedy
 * The Doctor meets journalist James Stevens.


 * PROSE: The Face of the Enemy: Prologue
 * The Doctor and Jo leave for Peladon, setting this during The Curse of Peladon.


 * TV: The Curse of Peladon
 * The Doctor visits Peladon for the first time.


 * PROSE: The Sommerton Fetch
 * The Doctor and Jo have the same outfits they wore in The Curse of Peladon.


 * PROSE: Spoilsport
 * PROSE: The Face of the Enemy: Epilogue
 * The Doctor and Jo return to UNIT almost immediately after The Curse of Peladon.


 * PROSE: Honest Living
 * Set shortly after The Curse of Peladon.


 * PROSE: The Switching
 * The Master changes the internal configuration of the Doctor's TARDIS, setting this after The Curse of Peladon, and before The Sea Devils, as the Master is sent to Fortress Island.


 * TV: The Sea Devils
 * Aided by the Sea Devils, whom the Doctor encounters for the first time, the Master is able to escape his prison sentence on Fortress Island.


 * PROSE: The Eight Doctors
 * Set immediately after The Sea Devils.


 * AUDIO: Find and Replace
 * Set after The Sea Devils, as the Doctor is making a device to track the Master and Jo has encountered the Daleks.


 * PROSE: The Seismologist's Story
 * COMIC: Under Pressure
 * Jo fails to recognise the Fourth Doctor, setting this before The Touch of the Nurazh.


 * TV: The Mutants
 * AUDIO: The Other Woman
 * Set after The Mutants, as Jo hasn't been in the TARDIS very often, the Master is free and the Doctor is anticipating being freed from his exile soon.


 * PROSE: Doctor Who Fights Masterplan "Q"
 * AUDIO: Prisoners of the Lake
 * Authorial intent places this between Day of the Daleks and The Time Monster.


 * PROSE: The Touch of the Nurazh
 * The events of The Mutants are mentioned.


 * PROSE: Where the Heart Is
 * The Doctor lists his work for the Time Lords, with The Mutants being the last one he mentions. This is also where UNIT acquires the manor house seen in The Three Doctors.


 * PROSE: Rags
 * Jo recalls the Daleks and Ogrons, which places this firmly after Day of the Daleks. Likewise, the Doctor confesses that sheep have never filled him with dread before, placing this before Verdigris.


 * TV: The Time Monster
 * PROSE: Morphology
 * A footnote states that this story takes place after The Time Monster.


 * AUDIO: The Scorchies
 * Jo is able to improvise a jamming machine, as she had seen the Doctor do in The Time Monster.


 * COMIC: Target Practice
 * PROSE: The Suns of Caresh: Prologue
 * The Doctor visits Professor Child's dig.


 * AUDIO: Tales from the Vault
 * The Doctor investigates a mysterious infantryman's jacket.


 * PROSE: Jigsaw
 * Set shortly before Verdigris.


 * PROSE: Verdigris
 * Ending leads directly into The Three Doctors.


 * TV: The Three Doctors
 * The Doctor's knowledge of time travel is restored to him as a reward for defeating Omega. However, he doesn't leave immediately, as he needs to fix up the TARDIS further.


 * PROSE: Verdigris: Epilogue
 * The Doctor's exile has just been rescinded.


 * PROSE: Hiccup in Time
 * With the TARDIS in his control again, the Doctor rescues Liz from 1539.


 * AUDIO: The Defectors
 * The Doctor is switched with his seventh incarnation by the Monk. Jo refers to the crisis of The Three Doctors, and, at the beginning, acts as if she hasn't traveled in the TARDIS yet, setting this shortly after that story.

Freedom

 * PROSE: The Wages of Sin
 * The Doctor goes on his first test flight into the past since his time travel knowledge was returned in The Three Doctors.


 * PROSE: Deep Stretch
 * The Doctor's exile has been recently lifted, but he still feels uneasy when it is mentioned.


 * AUDIO: The Many Deaths of Jo Grant
 * In the first artificial scenario, the Brigadier refers to the Doctor recently being released from his exile on Earth by the Time Lords.


 * PROSE: The Spear of Destiny
 * The Doctor has had his ability to pilot the TARDIS returned to him recently.


 * PROSE: Losing Track of Time
 * Jo is still new to time travel, but the Doctor has complete control of the TARDIS, setting this after The Three Doctors.


 * PROSE: Come Friendly Bombs...
 * The Doctor can control his TARDIS' flight, and Jo has apparently taken numerous lengthy trips in the TARDIS, setting this after The Three Doctors. This story also demonstrates her awakening social conscience, which leads into The Green Death.


 * AUDIO: The Havoc of Empires
 * This is Mike's first trip in the TARDIS, and the Doctor's exile has been rescinded by the Time Lords.


 * PROSE: Listen - The Stars
 * PROSE: Out of the Green Mist
 * COMIC: The Time Thief
 * PROSE: The Fathom Trap
 * The Doctor's exile has been recently lifted.


 * COMIC: Menace of the Molags
 * PROSE: Talons of Terror
 * PROSE: Old Father Saturn
 * PROSE: Galactic Gangster
 * TV: Carnival of Monsters
 * PROSE: The Suns of Caresh
 * The Doctor tries to recalibrate the TARDIS’ navigational system and Jo mentions having accidentally visited Inter Minor in Carnival of Monsters.


 * AUDIO: Seven to One
 * PROSE: The House That Jack Built
 * PROSE: Revenge of the Phantoms
 * COMIC: Dead on Arrival
 * PROSE: Fugitives from Chance
 * COMIC: After the Revolution
 * PROSE: The Battle Within
 * The Doctor and Jo have been travelling in the TARDIS for some time, but Jo is not familiar with the Doctor's trances, setting this before Frontier in Space.


 * AUDIO: The Mists of Time
 * Due to her memory trouble, Jo erroneously thinks this story happens immediately after The Doll of Death, but she later recalls the events of Day of the Daleks. As the TARDIS is free from Earth exile, this story must be set at least after The Three Doctors.


 * PROSE: Rock Star
 * Set between Carnival of Monsters and Frontier in Space.


 * PROSE: Lost and Founded
 * Set before Frontier in Space.


 * PROSE: Once upon a Time Machine
 * Set before Frontier in Space.


 * AUDIO: Pop-Up
 * TV: Frontier in Space
 * TV: Planet of the Daleks
 * Set immediately after Frontier in Space. At the end of this story, the Doctor and Jo decide to return to Earth.


 * PROSE: Catastrophea
 * Continues immediately on from Planet of the Daleks.


 * PROSE: The Piper
 * The Doctor has recently been to Spiridon, setting this after Planet of the Daleks.


 * PROSE: Nightdreamers
 * Jo is still musing on her romance with Latep from Planet of the Daleks, and begins to think about how her days with the Doctor might be coming to an end.


 * COMIC: Death to the Doctor!
 * PROSE: Dancing the Code
 * Set before Speed of Flight.


 * PROSE: Salt of the Earth
 * Jo has pale skin from spending lots of time inside the Doctor's lab.


 * PROSE: Hidden Talent
 * Latep from Planet of the Daleks is mentioned, and Jo has been back on Earth for “a bit.”


 * AUDIO: Time Tunnel
 * The events of The Three Doctors are alluded to.


 * AUDIO: Lost in the Wakefield Triangle
 * PROSE: Echoes
 * The Doctor seems able to control the TARDIS, and, although he speaks of Jo in the present tense, she is not traveling with him at the moment. Possibly set before Last of the Gaderene or Speed of Flight, where the Doctor is shown returning to UNIT after taking some solo trips.


 * PROSE: Potential
 * Set before The Green Death. Possibly set before Last of the Gaderene or Speed of Flight, where the Doctor is shown returning to UNIT after taking some solo trips.


 * PROSE: Speed of Flight
 * The Doctor is attempting to take Jo and Mike to Karfel, leading into the Third Doctor's part of Timelash.


 * TV: Timelash
 * Though he does not appear, the Doctor's trip to Karfel is mentioned throughout the episode, and evidence of him and Jo being there is also present.


 * PROSE: The Bad Guy
 * Set immediately after the Third Doctor's part of Timelash.


 * PROSE: Carpenter/Butterfly/Baronet
 * AUDIO: Ghost in the Machine
 * Jo refers to when the Doctor went into a coma during Planet of the Daleks.


 * PROSE: The Christmas Inversion
 * Mike is displeased to find himself traveling in the TARDIS, suggesting he has already travelled within it.


 * AUDIO: The Light at the End
 * The Doctor and Jo briefly encounter an apparition of a Charley Pollard from an alternate timeline.


 * PROSE: Legacy
 * The Doctor and Jo visit Pakha. The Doctor notices for the first time that Jo has grown up a lot since their first meeting.


 * PROSE: Hide and Seek
 * The Doctor notes that Jo is beginning to grow up.


 * PROSE: ...And Eternity in an Hour
 * Jo is familiar with the Doctor's trances that make his skin ice-cold, setting this after Planet of the Daleks.


 * PROSE: Categorical Imperative
 * The Doctor and Jo go back in time to kill a dictator as a baby. However, the Doctor sees his sixth incarnation doing the same, and leaves him to do it.


 * PROSE: Last of the Gaderene
 * This adventure takes place between Planet of the Daleks and The Green Death.


 * AUDIO: Sphinx Lightning
 * PROSE: The Dragon of Hyacinth Lodge
 * GAME: Destiny of the Doctors
 * Set during The Green Death: Episode 1, after the Doctor leaves Metebelis III and before he returns to UNIT.


 * TV: The Green Death
 * Jo leaves UNIT, and the Doctor's company, to marry ecologist Professor Clifford Jones.

Travelling alone

 * PROSE: She Knew
 * Set immediately after The Green Death.


 * PROSE: Midnight in the Café of the Black Madonna
 * Jo has just recently left the Doctor.


 * AUDIO: The Prisoner of Peladon
 * The Doctor still misses Jo after she left in The Green Death.


 * AUDIO: Council of War
 * Benton refers to the events of The Green Death.


 * COMIC: The Vogan Slaves
 * COMIC: The Celluloid Midas
 * COMIC: Backtime
 * COMIC: The Plant Master
 * COMIC: The Eternal Present
 * COMIC: *Sub Zero
 * COMIC: The Planet of the Daleks
 * COMIC: A Stitch in Time
 * PROSE: And Now for My Next Trick...
 * COMIC: The Enemy from Nowhere
 * COMIC: The Ugrakks
 * COMIC: Steelfist
 * COMIC: Ride to Nowhere
 * AUDIO: A True Gentleman
 * COMIC: Zeron Invasion
 * PROSE: Countdown to TV Action
 * This story takes place between Zeron Invasion and Deadly Choice.


 * COMIC: Deadly Choice
 * COMIC: Who is the Stranger
 * COMIC: The Glen of Sleeping
 * COMIC: The Threat from Beneath
 * COMIC: Back to the Sun
 * COMIC: Fogbound
 * PROSE: Smash Hit
 * COMIC: Secret of the Tower
 * PROSE: The One Second Hour
 * COMIC: The Labyrinth
 * COMIC: The Spoilers

Adventuring with children

 * COMIC: The Vortex
 * COMIC: The Unheard Voice
 * COMIC: The Hungry Planet
 * COMIC: Children of the Evil Eye
 * COMIC: Nova
 * COMIC: The Amateur

Alone again

 * PROSE: Dateline to Deadline
 * Set between The Green Death and The Time Warrior.


 * COMIC: The Disintegrator
 * COMIC: Is Anyone There?
 * COMIC: Size Control
 * COMIC: The Magician
 * PROSE: Dream Devils

Meeting his other incarnations

 * PROSE: All-Consuming Fire
 * PROSE: The Juror's Story
 * TV: The Day of the Doctor
 * PROSE: The Glass Princess
 * COMIC: Day of the Tune
 * AUDIO: The Three Companions
 * AUDIO: The Time Vampire
 * The Doctor and Joshua Douglas part ways after ten years of companionship.


 * PROSE: Downtime
 * PROSE: Faithful Friends: Part 1
 * Set before The Time Warrior.

Meeting Sarah Jane Smith

 * TV: The Time Warrior
 * The Doctor meets Sarah Jane Smith, who becomes a reluctant stowaway aboard the TARDIS.


 * AUDIO: The Paradise of Death
 * Set immediately after The Time Warrior, with the Doctor returning Sarah to her home after that adventure. She decides to officially join the Doctor's company.

Exploits with Sarah

 * PROSE: Before the Legend
 * Sarah Jane doesn't know much about the Doctor's origins.


 * PROSE: The Time Thief
 * The Doctor tells Sarah Jane about Gallifrey and Time Lords.


 * PROSE: Scorched Earth
 * TV: Invasion of the Dinosaurs
 * PROSE: Neptune
 * The Doctor is trying to get Sarah to Florana, as he promised in Invasion of the Dinosaurs.


 * PROSE: Numb
 * Set shortly after Invasion of the Dinosaurs.


 * TV: Death to the Daleks
 * The Doctor and Sarah are traveling to Florana for a holiday, setting this almost immediately after Invasion of the Dinosaurs. Sarah Jane has her first encounter with the Daleks.


 * PROSE: Interesting Times
 * Set after Death to the Daleks.


 * PROSE: The Hungry Bomb
 * Set between Death to the Daleks and The Monster of Peladon.


 * AUDIO: The Light at the End
 * COMIC: In With the Tide
 * The Doctor is driving the "Whomobile", setting this after Invasion of the Dinosaurs. The Doctor and Sarah have been absent from UNIT long enough for it to have been infiltrated by the Remoraxians.


 * COMIC Endgame
 * AUDIO: The Ghosts of N-Space
 * Sarah knows about the Daleks, setting this after Death to the Daleks.


 * TV: The Monster of Peladon
 * PROSE: Alien Bodies
 * Sarah Jane and the Doctor have just left Peladon, setting this after The Monster of Peladon.


 * PROSE: Interference - Book One / Book Two
 * Set immediately after Alien Bodies. Interference presents an alternate regeneration scene in which the Third Doctor regenerates in on Dust. The paradox of this is resolved in The Ancestor Cell.


 * PROSE: Separation Day
 * Sarah is wearing the leather jacket seen in The Monster of Peladon.


 * PROSE: The Dead Man's Story
 * Set after The Monster of Peladon.


 * PROSE: Sedna
 * Sequel to Neptune. The Doctor is traveling alone with Jeremy Fitzoliver, setting it after The Dead Man's Story.


 * PROSE: Link
 * Set after The Monster of Peladon.


 * AUDIO: Glorious Goodwood
 * Sarah recalls meeting the Aggedor on Peladon, setting this after The Monster of Peladon.


 * COMIC: Who's Who?
 * COMIC: Doomcloud
 * COMIC: Perils of Paris
 * PROSE: Signal S.O.S.
 * PROSE: A Visit from Saint Nicholas
 * Set after The Monster of Peladon.


 * PROSE: Amorality Tale
 * This adventure takes place between The Monster of Peladon and Planet of the Spiders.


 * PROSE: The Discourse of Flies
 * Sarah has already been to a number of alien worlds.

Time alone

 * PROSE: Five Card Draw
 * Though she is absent, the Doctor is currently traveling with Sarah.


 * COMIC:  The Metal-Eaters
 * COMIC: Petrified
 * COMIC: Lords of the Ether
 * COMIC: The Wanderers
 * TV: The Name of the Doctor
 * Set immediately before The Five Doctors.


 * TV: The Five Doctors
 * The Doctor recognises Sarah Jane when he encounters her future self in the Death Zone, setting this during Season 11.

Final exploits

 * PROSE: Island of Death
 * Sarah mentions her vacation in Sicily, placing this after The Ghosts of N-Space.


 * PROSE: Primitives
 * PROSE: The Lampblack Wars
 * PROSE: Generation Gap
 * PROSE: An Overture Too Early
 * Set shortly before  Planet of the Spiders.


 * TV: Planet of the Spiders (Episode 1–Episode 6)
 * Confronting the Great One of the Eight Legs, the Doctor receives a lethal dose of radiation, but is able to escape in the TARDIS.

A slow demise

 * In Love and War, it is revealed that the Doctor was stuck wandering around the time vortex for ten years before regenerating.


 * PROSE: Ancient Whispers
 * Slowly dying from radiation sickness, the Doctor is trying to find his way back to UNIT HQ from Metebelis III.


 * PROSE: The Loneliness of the Long-Distance Time Traveller
 * The Doctor is dying after being exposed to radiation.


 * TV: Planet of the Spiders: Epilogue
 * After the TARDIS finally lands back at UNIT HQ, the Doctor is able to regenerate into his next incarnation with assistance from K'anpo Rimpoche.