Rassilon

Rassilon is a fictional character from the British science fiction television series Doctor Who. In the backstory of the programme, he was the founder of Time Lord society on the planet Gallifrey and its first leader. Rassilon was first mentioned in the 1976 serial The Deadly Assassin, where he was retconned into being a major establishing figure in Time Lord society, filling the role previously fulfilled by the character Omega. Despite his impact on Time Lord society, he was implied to be a cruel leader. He would later appear in the 1983 episode "The Five Doctors" in a physical appearance. In the show's revival, he appears as an antagonist in the 2009–2010 episodes "The End of Time" and the 2015 episode "Hell Bent". Rassilon has also appeared in a large amount of spin-off media associated with the show.