In the Irish side story, we see Brendan as the incarnation of The Doctor/TC.

Little is known of The Other, but there have long been theories that The Other is an incarnation of The Doctor. Ruling the High Council (and the Supreme Council) is the Triumvirate: Rassilon, Omega, and the Other. Rassilon is a charismatic leader who is capable of inspiring his people. Rassilon and Omega are politically opposed, but despite this they are friends. COMIC: Star Death, The Final Chapter, Wormwood: Rassilon and Omega made the star Qqaba go supernova to become Lords of Time. Omega is a fictional character from the long-running British science fiction television series, Doctor Who.In the context of the series, Omega is known as one of the founders of the Time Lords of the planet Gallifrey, and is a revered figure in Time Lord history together with the equally legendary Rassilon; the Third Doctor refers to him as the Time Lords' "greatest hero". Rassilon is 1st President of the High Council and sits upon the Kasterborian Throne. After the loss of Omega, Rassilon … He was a Time Lord who was the compatriot of Rassilon and was responsible for giving the Time Lords the ability to time travel. He was generally considered the first Time Lord, though some believed that distinction belonged to his compatriot Omega.

He was portrayed by the late Stephen Thorne in 1972 and 1973, and the late Ian Collier and Peter Davison (in the form of the Fifth Doctor) in 1983.
I've accidentally put the images of the chapter seals in the wrong order and I can't seem to fix them, so just to clarify, the names of the seals go with the order of the first picture, left to right. Rassilon is the first and only President to hold the title 'Lord High President.'

Rassilon was, alongside Omega and the Other, one of the founders of Time Lord civilisation and widely regarded as the single greatest figure of Gallifreyan history. Omega is a major antagonist in the Doctor Who franchise. Rassilon stole Fenris’ directional control device, completing his “invention” of time travel. Rassilon built on Omega’s work and expanded politically and militarily to set Gallifrey up on the pedestal they later enjoyed.

However, he is also a sanctimonious and fraudulent hypocrite, becoming corrupted by power (despite his supposed opposition to such corruption) and increasingly obsessed with avoiding death. In order, Rassilon's seal, Omega's seal, Lazuline's seal, Apeiron's seal, Eutenoyar's seal, and Pandak's. Omega was killed by the time traveler Fenris the Hellbringer. He was was in turn (indirectly) killed by Rassilon.