Seal of Rassilon
Rassilon was the Legendary Founding Father of Time Lord Society on Gallifrey. In Gallifreyan lore, Rassilon was the Wise Lawgiver about whom there are many myths and legends. The myth establishes him as a man of Great Passions as well as being a leading Scientist within Gallifrey's scientific elite. He is credited with replacing a culture of Superstition and Magic with an age of Science and Reason. Collaborating with Omega, he developed the technology that would make his people Lords of Time but, as a consequence, Gallifrey was plunged into a series of conflicts across time and space.
The greatest of his legends lies in the mystery of his death, and the belief that he achieved the Secret of Perpetual Regeneration - true immortality unfettered by the restraints of Gallifreyan technology.