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 from the TARDIS Data Core article, licensed under CC-BY-SA}