Mawdryn Undead Databank

The Black Guardian contacts the alien Turlough, who is living amongst boys at an English boarding school where the Brigadier is now teaching math. The Guardian wants Turlough to kill the Doctor. The TARDIS, meanwhile, has brought the Doctor, Nyssa and Tegan to a space station trapped in a warp ellipse. It serves as a prison for a team of scientists led by Mawdryn, who tried to steal the secrets of the Time Lords and were placed in a state of perpetual regeneration as retribution. It is up to the Doctor to find some way to help Mawdryn, but doing so may cost him his remaining regenerations.

BLACK GUARDIAN 
A conceptual entity embodying Darkness and Chaos. He used the Shadow to stop the Fourth Doctor from claiming Princess Astra of Atrios, the sixth segment of the Key to Time. After the Doctor defeated the Shadow, he assembled the Key and outwitted the Black Guardian, enabling the White Guardian to restore the universal balance (5F). The Black Guardian swore revenge against the Doctor and, later, used Turlough to try to kill the Fifth Doctor (6F, 6G)
BLINOVITCH LIMITATION EFFECT 
One of the laws of Time Travel. It dealt with a traveller meeting his other selves. It was invoked by the Third Doctor. The Fifth Doctor used it to explain the energy released when the 1977-Brigadier met the 1983-Brigadier in Mawdryn's ship (6F).
CASSIDY (MISS) 
Matron at Brendon School (6F).
CHAOS 
The concept of Chaos and Darkness were embodied by the Black Guardian (5F, 6F-6H).
DARKNESS 
The concept of Chaos and Darkness were embodied by the Black Guardian (5F, 6F-6H).
HEADMASTER 
Unnamed Headmaster at Brendon School (6F).
IBBOTSON 
Turlough's lumpish school friend at Brendon (6F).
MAWDRYN 
Leader of a team of eight alien scientists who stole a Metamorphic Symbiosis Regenerator from Gallifrey. This created an unending life of perpetual mutation, their bodies eternally renewed into vile travesties of their former selves. Their ship was caught in a warp ellipse but, every seventy years, space beacons guided it within transmat distance of Earth. Mawdryn claimed that only the life force of a Time Lord's incarnation could put an end to their misery. The Fifth Doctor was ready to sacrifice his remaining regenerations, however, the energy released by the meeting between the 1977 and 1983 Brigadiers was enough to end the lives of Mawdryn and his fellow aliens (6F).
METAMORPHIC SYMBIOSIS REGENERATOR 
Machine used by the Time Lords in cases of acute regenerative crisis. It was stolen from Gallifrey by Mawdryn and seven alien scientists. Used by them, it created an unending life of perpetual mutation, their bodies eternally renewed into vile travesties of their former selves. Mawdryn claimed that only the life force of a Time Lord's incarnation could put an end to their misery. The Fifth Doctor was ready to sacrifice his remaining regenerations. However, the energy released by the meeting between the 1977 and 1983 Brigadiers was enough to end the lives of Mawdryn and his fellow aliens (6F).
PORTON DOWN 
The Brigadier told the Fifth Doctor that Harry Sullivan had been seconded to NATO, and was involved in a secret operation at Porton Down (6F).
RUNCIMAN (DR.) 
Medical doctor at Brendon school (6F).
SULLIVAN, HARRY 
One of the Fourth Doctor's Companions. He was Surgeon-lieutenant of UNIT. The Brigadier entrusted the Fourth Doctor to his care just after his regeneration. Harry helped him and Sarah Jane Smith fight the Scientific Reform Society and Prof. Kettlewell's Giant Robot. He then accompanied the Doctor and Sarah in the TARDIS, and fought against the Wirrn, the Sontaran Styre, the Cybermen on Voga (at which time the Doctor proclaimed that he was an "imbecile"). He was present when Davros created the Daleks. After fighting the Zygons, he chose to remain on Earth (4A-4F). He helped the Doctor again against the Kraals, who had made an android duplicate of him (4J). The Brigadier later told the Fifth Doctor that Harry had been seconded to NATO, and was involved in a secret operation at Porton Down (6F).
TREVOR 
One of Brendon School pupils
TRUMPER 
One of Brendon School pupils (6F).
TURLOUGH, VISLOR 
One of the Fifth Doctor's Companions. When the Time Lord met him, Turlough was a schoolboy on Earth at Bendon School. After a minor car accident, he entered into a pact with the Black Guardian to kill the Doctor. During their adventure on Terminus, he made several half-hearted attempts, but failed. Finally, after the encounter with the Eternals, Turlough turned against the Black Guardian and, by throwing the Enlightenment crystal at him, freed himself. Afterwards, he helped the Doctor fight the Master. He then met the Doctor's First, Second and Third Incarnations on the Dead Zone of Gallifrey, and helped them defeat Borusa. Turlough went on to assist the Doctor in his battles against the Silurians and the Sea Devils, the Malus, the Tractators and the Daleks. Finally, Turlough was revealed to be a political prisoner from Trion sentenced to ten years' exile on Earth. After another battle against the Master on Sarn, Trion's prison planet, Turlough found that his exile had been rescinded. He returned to his homeworld with his newly-found brother, Malkon. As a Trion political prisoner, Turlough had been tattoed with the Misos Triangle (6F-6Q)
TURNER 
One of Brendon School pupils (6F).
WARP ELLIPSE 
Condition of an object placed in a fixed orbit in time as well as in space. Mawdryn's ship was in a warp ellipse above Earth (6F).