Eldrad Eldrad was a Kastrian who developed many scientific marvels for his people . He regarded himself as the " creator of Kastria " , such was his contribution to life on the planet . Eldrad ' s dreams of galactic conquest led him to betray his race and he was sentenced to death and obliterated . Parts of Eldrad were scattered across space , allowing for his revival in many different incarnations . Both the Doctor and Mulkris , a Kastrian executioner , had a hand in destroying these remnants . Biography . Millennium War . 150 million years ago during the Millennium War against the Mad Mind of Bophemeral , Eldrad ' s Kastrian fleet was utterly destroyed and their own computer s were turned against them , laying waste to Kastria . ( PROSE : " The Quantum Archangel " ) Scientific work . In order to protect Kastria , homeworld of the Kastrians , from solar wind s , Eldrad developed spatial barrier s that allowed life to exist on the planet ' s surface and revitalised the planets earth and air . He developed a " crystalline silicon form " for the physical needs of the Kastrians . Eldrad designed the regenerator chamber — a device that used irradiation to revitalise — and programmed it to his own ends , ensuring it could never be used to cause him harm . He produced an acid that neutralised the molecular bond of Kastrians when they were imbued with it . Eldrad had a ring which contained a crystal with his genetic code . This allowed him to reconstitute his physical form from any radioactive material . He called it his " key to eternity " . Treachery . Eldrad dreamed of galactic conquest , with the Kastrian race seizing all the planets in range of their spacecraft . However , King Rokon opposed him in this . Angered by this denial , Eldrad destroyed the barriers , allowing the solar winds to ravage the surface of Kastria . For his crime , Eldrad was sentenced to death and place in an obliteration module that was launched into space . In order to ensure its occupant was completely destroyed , it had to be activated twenty - five span s from Kastria . However , as there was a risk the solar winds would leave Outer Dome Six with no control over the craft , it was detonated prematurely — at nineteen spans . ( TV : " The Hand of Fear " ) The composite parts of Eldrad were scattered across many worlds . The hand and the eye both ended up on Earth , the former doing so in the Jurassic era . ( AUDIO : " Eldrad Must Die ! " , " The Hand of Fear " ) Revival of the hand . One hundred and fifty million years later , in the late 20th century , blasting work at a quarry in England brought a stratum to the surface composed of blackstone dolomite — Jurassic limestone . The Fourth Doctor and Sarah Jane Smith were covered by the residue of the blast . Buried beneath rock , Sarah reached out to a hand she believed to be the Doctor ' s , but found it to be stone — the hand of Eldrad . Sarah was the first person the hand had come into contact with since its arrival on Earth and she fell under the influence of Eldrad , hearing his commands in her mind . Waking in hospital , she used the ring of Eldrad to render Doctor Carter unconscious and took the hand . When he woke , he too was hearing Eldrad ' s commands . Sarah travelled to Nunton Experimental Complex where she took the hand into the reactor room . Eldrad began absorbing radiation and the hand began to move . Carter , under the Kastrian ' s influence , attempted to stop the Doctor from interfering and fell to his death in doing so . The Doctor reached Sarah and took her away from both the hand and the ring . Driscoll , a worker at the complex , found the jewel and so became the new puppet of Eldrad , Sarah no longer being under his control . Driscoll took the hand into the reactor core where Eldrad regained a full humanoid form . It was based on Sarah — the first being it hand come into contact with — in order to appear familiar , and so was female . The military launched missiles at the complex , but they were absorbed by Eldrad to complete the restoration . She read the mind of the Doctor to ascertain knowledge — specifically whether or not what he told her about the passage of time was true . Knowing him to be a Time Lord , Eldrad asked to be taken back in time to Kastria , but the Doctor refused on the basis of the Laws of Time . Eldrad told Sarah and the Doctor that a war between two planets had destroyed the barriers of Kastria and she had been discredited and sentenced to death in the wake of this . Professor Watson shot at Eldrad and she pursued him to the control centre and attacked him — intending to kill him — but was persuaded by the Doctor to let him live . Back to Kastria . Travelling in the Doctor ' s TARDIS , Eldrad returned to Kastria . The planet was now cold and barren as a result of solar wind activity . While attempting to access the thermal chamber s , subterranean dwellings of the Kastrian people , Eldrad triggered a booby trap . It fired a dart at her containing the acid she developed . The traps had been devised by the Kastrians , who were aware of her possible return . Knowing there to be no antidote , Eldrad requested that the Doctor take her underground to the regenerator chamber . The Doctor and Sarah had to carry her most of the way — including over an abyss — and deactivated a further trap on the door of the chamber . They placed Eldrad in the chamber and the Doctor activated it . Eldrad was restored to his male or , as he called it " true " , form . The machine had been altered to function as a trap , but Eldrad laughed at this , knowing his own programming prevented it from harming him . Having received a message from Rokon , Eldrad searched the city for the king . He found his body and was angered , feeling he had been cheated of his destiny . Eldrad decided to used the regenerator to recreate his species from the race bank , but on going there , found it empty . From another recording of Rokon ' s , he learnt that the Kastrian people had " [ chosen ] final oblivion " rather than have to face the subterranean existence the destruction of the barriers consigned them to . Furthermore , fearing that Eldrad would use the race banks to " wage eternal war throughout the galaxy " they elected to destroy them . Earth was seen as an alternative by Eldrad , who hoped to harness the aggressive trait of the human race and have them worship him as a god . The Doctor refused to take him back . Eldrad requested that the Doctor return his ring . The Time Lord threw his magician ' s stick into the race bank , which Eldrad took to be the jewel , distracting him . The Doctor and Sarah fled , pursued by Eldrad , who still hoped to be taken to Earth . The time travellers poised themselves next to the abyss they had carried the female Eldrad over and each held an end of the Doctor ' s scarf . Pulling it taut , Eldrad tripped and fell into the depths . The Doctor tossed the ring down after him . Back in his TARDIS , the Doctor doubted Eldrad was dead , being " very difficult to kill " . Of Eldrad ' s different genders , Sarah said she " quite liked her , but [ she ] couldn ' t stand him " . ( TV : " The Hand of Fear " ) Revival of the eye . The eye of Eldrad came to be called the " watcher " . The Kastrian Mulkris , tasked by Rokon with finding parts of Eldrad and putting them into a stasis field , came to Earth in search of the eye . In 2013 , she took control of Charlie Gibbs who bought the watcher from Rocco and handed it to Vislor Turlough , who was also under her control . Gibbs looked at the eye directly and fell under Eldrad ' s influence instead . Seizing the eye , it lodged itself in his forehead . The Ambermouth harbour became covered in silicon quartz , the makeup of Kastrians , and part of Eldrad ' s plan to have the Earth become the centre of his galactic empire . The crystals would provide the planet , and the humans who were also infected , with a hard armour , making them suitable for war . Gibbs went to Mulkris and killed her with the acid Eldrad developed . The Fifth Doctor took Gibbs to Kastria , where he hoped to find Eldrad ' s ring and use it to restore his physical form . Eldrads of the eye and the hand . The Eldrad born from the hand survived the fall . He had dragged himself from the abyss and carved an inscription upon himself : " here lies Eldrad . I am alive , but unliving " . Eldrad built a throne for himself and became a size twice that he was before . In his solitude , he became mad , talking to the dust that surrounded him , the remains of dead Kastrians . When the Fifth Doctor , Tegan , Turlough and Gibbs arrived on Kastria , they took it to be a statue . Gibbs ordered Turlough , who was under his influence , to take the ring from the hand . In doing so , he was woken . Gibbs tapped into the power of the Doctor ' s TARDIS and channelled it through the dust , restoring Eldrad in his image by absorbing the resultant radiation . This Eldrad labelled his predecessor old , declaring his intent to found an empire centred around the Earth , leaving Kastria — a " tomb " — to the Eldrad of the hand . The old Eldrad used a dart of the acid to kill the Eldrad of the eye . Connecting the presence of a TARDIS to his visitors , Eldrad identified the Doctor and recounted his dreams of their meeting again so he could kill his " persecutor " . He attacked the Doctor , but was distracted by the arrival of Mulkris , restored by the presence of her own genetic ring in the TARDIS . Tegan and Turlough , armoured by crystals to the point where their arms were weaponised , destroyed Eldrad ' s ring . Mulkris then used the dart used to kill the Eldrad of the eye against that of the hand , killing him . Other revivals . On other worlds , Mulkris encountered " a hundred false Eldrads " who she killed . After the death of the Eldrad that grew from the hand , she invited Turlough to journey with her in search of further fragments , but he declined . ( AUDIO : " Eldrad Must Die ! " )