Rassilon

Rassilon is a Time Lord who founded Time Lord society and created regeneration.

Biography
Rassilon founded Time Lord society. He gave Gallifreyans the ability to regenerate after saying that they will never truly die. He also created the Matrix, in which could contain the minds of Time Lords after they run out of regenerations and die. (AUDIO: The Library in the Body (audio story), The Deadly Assassin (TV story))