Rassilon is a fictional character in 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, as Lord High President. After the original television series ended in 1989, Rassilon's character and history were developed in books and other media. Character history Within the universe of the television series, there are many contradictory legends about Rassilon. It is known that he developed the technology for time travel that made his people lords of time in the distant past together with his colleague Omega. Omega, a stellar engineer, was presumed killed by the supernova that created the black hole later known as the Eye of Harmony, and Rassilon harnessed the nucleus of the black hole to provide the energy that powers time travel. Rassilon then took control of Gallifrey and became the first and, to date, only Lord High President, his successors taking the title Lord President. The official history is that he was a benevolent ruler who ruled his people wisely. However, there are other accounts which paint Rassilon as a cruel dictator, opportunistic and ambitious who seized power in the wake of his friend's death (for which some suggest he may have been deliberately responsible), and ready to take drastic measures to protect his people, nearly destroying all of time once. Rassilon's contributions to Time Lord culture and society were immense, and his name both reverberates and is honoured throughout Time Lord history. The Rassilon Imprimatur is the name given to the symbiotic nucleus of Time Lords' cell structures that allows them to withstand the molecular stresses of time travel and grants them a link to their TARDIS time machines. Several other Time Lord artifacts named after him have a technological function, in addition to their ceremonial roles: The Sash of Rassilon allows the wearer to be in close proximity to the singularity that is the Eye of Harmony, providing protection from the Eye's gravitational and energy forces, and preventing the wearer from being drawn across the event horizon of the captured black hole. Use of the Sash in this way is cited as having a regenerative effect upon the wearer. The Crown of Rassilon (or matrix circlet) gives full access to the Matrix, providing a direct mental link to the computer network that serves as the repository of all