Eldrad

Eldrad was a Kastrian overlord who was sentenced to death and obliterated.

Biography
A hundred fifty million years before the 20th century, Eldrad was a brilliant scientist who created a barrier to protect Kastria from the solar winds, as well as new, silicon-based bodies for the Kastrians to deal with the environment. He planned to make his people into aggressors, leading to a revolt. Led by King Rokon, the Kastrians captured Eldrad and placed him in an obliteration module detonated by remote control. Though he was almost entirely destroyed, one of his hands and his ring survived and somehow came to primordial Earth.

Eldrad's damaged and petrified hand was found in an English quarry after an explosion. Having just arrived on Earth in the TARDIS with the Fourth Doctor, Sarah Jane Smith was caught in the blast and found the hand. Eldrad's ring took control of her mind, forcing her to go to the nearby Nunton Experimental Complex, which had a nuclear reactor.

Though the Doctor saved Sarah from Eldrad's powers, the ring also influenced Dr. Carter and Driscoll, who worked to help Eldrad regenerate. Eldrad made Driscoll take his hand into the core of the reactor. Eldrad employed the reactor's radiation to completely regenerate into a form modelled on Sarah, the ring having taken her imprint.

Eldrad claimed she had been overthrown after a war between her people and another race, and asked to be returned to her homeworld. The Doctor agreed to take Eldrad to Kastria, but refused to go into the past. Once in the Kastrian base, Eldrad was poisoned by an acid harpoon, which started to break down her system. With the help of the Doctor and Sarah, she reached a regeneration chamber before her structure broke down.

Restored to his true Kastrian form by the regeneration chamber, Eldrad planned to take back Kastria and then the universe, until he learnt of the fate of the Kastrians. Led by Rokon, they had chosen suicide for their race rather than risk the small chance of Eldrad returning to lead them. Eldrad decided to return to Earth in the TARDIS and enslave the humans there.

The Doctor stole Eldrad's ring, causing Eldrad to pursue him. Chasing the Doctor, Eldrad tripped over his scarf and into a deep chasm. Though Eldrad now seemed to have died, the Doctor expressed doubt about his demise. (DW: The Hand of Fear)

Powers and Abilities
In addition to the abilities of regeneration and metamorphosis granted him by his silicon-based form, Eldrad could use telepathy. His hand could control the minds of humans who had seen the light of his ring. In his female form, she attempted to hypnotize the Doctor. When she did so, her eyes glowed bright blue. (DW: The Hand of Fear)