In a story arc stretching through several of the Eighth Doctor Adventures, sometime in the Doctor's future, a war is fought between the Time Lords and an unnamed Enemy, the Eighth Doctor becoming involved in the events of the war during the events of Alien Bodies, when he unintentionally becomes involved in an auction for the body of his future self due to his biodata codes being the only means of accessing dangerous Time Lord secrets, and The Taking of Planet 5, where he must stop a group of future Time Lords from releasing the monstrous Fendahl in an attempt to use it as a weapon.

In an essay in About Time, a critical analysis of classic Doctor Who, Lawrence Miles and Tat Wood suggest that Planet 14 may be Telos, placing that planet as the fourteenth in our own solar system, after Mercury, Venus, Earth, Mondas, Mars, the time-looped planet mentioned in Image of the Fendahl, Jupiter, Saturn, Uranus, Neptune, Pluto, " Cassius " ( mentioned in The Sun Makers as a planet beyond Pluto ) and " Xena " ( a name popularly used for the dwarf planet Eris prior to its official naming ; in the essay, Miles and Wood confuse it with Sedna, another trans-Neptunian object discovered by the same team of astronomers ).

Some of the plays in the series also feature the Fendahl, a race of creatures also created by Boucher for the Doctor Who story Image of the Fendahl.

However, the fifth play Checkmate by Alan Stevens takes the theme of manipulation to a higher level, introducing the Fendahl from Boucher's Doctor Who serial Image of the Fendahl as the series ' major villain, manipulating events in Kaldor City to ensure its own emergence.

Checkmate by Alan Stevens continues directly after the events of Taren Capel, and whilst it ostensibly deals with Uvanov and Iago's struggle to contain the threat of the killer robots, it becomes clear as the play progresses that another plot is being hatched: the Church of Taren Capel seem more concerned with Capel's skull than his diaries, and eventually this is used to bring forth the Fendahl.

This seems to involve him going back in time and killing his lover, although this may all have been an illusion created by the Fendahl for its own ends.

He and his followers capture Colby, kill Fendelman, who was actually influenced through his genetics by the Fendahl to bring this about, and set up the Sonic Time scanner to power the skull and Thea's final transformation.

While investigating the distortion, he and Leela are confronted by an ancient being that feeds on death from Time Lord history, called the Fendahl ( Image of the Fendahl ).

In Image of the Fendahl ( 1977 ), the Fourth Doctor suggests that nine million years prior to the 20th century, the malevolent entity known as the Fendahl passed by Mars on its way to Earth, fleeing the efforts of the Time Lords to trap it forever in a time loop.

Image of the Fendahl is the third serial of the 15th season in the British science fiction television series Doctor Who, which was first broadcast in four weekly parts from 29 October to 19 November 1977.

Lill twice appeared in the BBC's science fiction series Doctor Who: as Dr Fendelman in the 1977 serial Image of the Fendahl and as Sir George Hutchinson in 1984's The Awakening.

However, there are episodes that seem to contradict this view, or at least to point to a relaxation of it: " Genesis of the Daleks ," where the Time Lords ask the Doctor to prevent the creation of the Daleks or at least change them into a less violent race, " Image of the Fendahl ," where the Time Lords destroyed the fifth planet of Sol and then used a Time Loop to hide all records of its existence, and " Two Doctors ," where the Time Lords enlist the aid of the Doctor to prevent the independent development of their method of time travel.

A number of episodes involve or make mention of a time loop ( also referred to as a " chronic hysteresis "): " Image of the Fendahl ", " Carnival of Monsters ", " The Invasion of Time ", " The Armageddon Factor ", " The Claws of Axos ", " Meglos " and " Father's Day " ( a car is stuck in a time loop after history is changed as the universe seemingly tries to ' restore ' history ).

He improvises non-lethal weaponry when necessary ( Genesis of the Daleks ), but was also not averse to more lethal weaponry as a necessity against both sentient and non-sentient beings, like the matter-destroying DeMat Gun ( The Invasion of Time ) or contemporary firearms ( Image of the Fendahl and The Talons of Weng-Chiang ).

She has appeared in Doctor Who on three occasions over three decades: playing Jean Rock in The Faceless Ones ( 1967 ), Thea Ransome in Image of the Fendahl ( 1977 ) and Faroon in Time and the Rani ( 1987 ); and had a small role in the science fiction drama The Prisoner, and the sitcoms Executive Stress and Next of Kin.

More specifically, the 1971 & 1977 Doctor Who serials The Dæmons and Image of the Fendahl contain many very similar elements and themes to Quatermass and the Pit.

Similar themes also appear in Image of the Fendahl which deals with beings, the Fendahl of the title, that after the destruction of their homeworld came to Earth and influenced the evolution of humans to possess psychic powers.

In science fiction, he wrote three Doctor Who serials in the late 1970s: The Face of Evil, The Robots of Death and Image of the Fendahl.

The same location would be used during the filming of Image of the Fendahl.

Taren Capel also saw the apparent departure of Carnell, although the character may have possibly returned in the following play: it is likely, however, that the Carnell in Checkmate was a projection of Iago's mind and / or the Fendahl rather than the actual psychostrategist.

At the close of the play, Iago is shot and apparently dying when the Fendahl ( through Iago's paramour ) offers him a deal.

The Fendahl also appears in the play, apparently manipulating the crew and one of its robots for its own ends, and it has been suggested that in fact the play is demonstrating what it feels like for the characters to be assimilated into the Fendahl's gestalt entity.

Developing psychic abilities due to spending one's childhood near a time fissure was first established in Image of the Fendahl.

Thea, meanwhile, has been gradually converted into the new core of the Fendahl, a creature that feeds off life energy and leaves nothing behind.

Stael, leader of the local black magic cult, recognises this and believes he can control the Fendahl and use it to dominate.

The Doctor, Leela, Ma Tyler and her grandson Jack head for the priory only to find the Fendahl core has formed and is converting the cult members into Fendahleen, to form the full circle.

The Doctor frees Colby and helps Stael shoot himself after killing one of the new Fendahleen, in turn finding out that the Fendahleen are fatally allergic to Salt, leaving the Fendahl core two short of the twelve it needs to be complete and form a gestalt.

The Doctor rigs the scanner to implode upon itself and grabs the now dormant skull, leaving with the others only just before the priory is destroyed, along with the Fendahl core and the remaining Fendahleen.

The Doctor and Leela then leave and plan to dump the skull near a supernova, thus ending the Fendahl race forever.

Wesley reappears in the first season ( 1999 – 2000 ) of spin-off show Angel, in the episode " Parting Gifts ".

* The Inquisitor reappears in most of the episodes of the Big Finish spin-off audio series Gallifrey.

She reappears in a spin-off series The Body Farm.

The Cardiff rift reappears in the episodes " Boom Town " and " Utopia ", and is a direct or indirect element in many of the alien encounters in the spin-off series Torchwood, set in Cardiff.

* The character of Ann Talbot reappears in the spin-off novel The Sands of Time by Justin Richards as Lady Ann Cranleigh.

* The character of Tobias Vaughn reappears in the Virgin New Adventures spin-off novel Original Sin by Andy Lane, in which he meets the Seventh Doctor.

The novel introduces the character of Granny Weatherwax, who reappears in several later Discworld novels.

Dorothy first appears in Baum's classic children's novel The Wonderful Wizard of Oz and reappears in most of its sequels.

* Tommy Tigertail, the only surviving member of Las Noches, reappears, peripherally, in Hiaasen's novel Nature Girl.

Masteen disappears during the events of Hyperion, but reappears near the end of the novel and is found at the beginning of The Fall of Hyperion.

Wodehouse referenced Aram even earlier, in Chapter 21 of his 1905 novel The Head of Kay's, when the hero Fenn loses his school cap in a possibly incriminating situation, and notes, when it reappears, that:

Susan reappears in the Eighth Doctor Adventures novel Legacy of the Daleks by John Peel, which takes place after the events of The Dalek Invasion of Earth.

Ayrton reappears in Verne's later novel, L ' Île mystérieuse ( The Mysterious Island, 1874 ).

He reappears from time to time, poping up, like a jack-in a box, whenever he isn't wanted, as the story progresses ; d ' Artagnan regularly sees Rochefort and tries to catch him, however, he vanisheses into the streetcorner crowds of Paris, skillfull, and never gets to actually meet him again and learn his name until the end of the novel.

He reappears in other footnotes throughout the opening but does not appear as a character in the text proper until a quarter of the way through the novel.

A Gancanagh named Joshua Kindler is a major character in Tim Pratt's Marla Mason novel Poison Sleep, and reappears in Broken Mirrors.

* Anne Travers also reappears in The Web of Fear and the Virgin Missing Adventures novel Millennial Rites, which also features the Great Intelligence.

Canon Tallis reappears in the Austin family novel The Young Unicorns, where he is attached to the Cathedral of St. John the Divine in New York City, the same cathedral where Madeleine L ' Engle was writer in residence for many years.

She reappears as the narrator of Bryant's short novel Fetish.