Azmael

Azmael was a benevolent renegade Time Lord who emigrated from Gallifrey to the planet Jaconda, a planet of flightless bird people where he settled and ruled there benevolently until Mestor deposed him.

Biography
On Gallifrey, Azmael worked as Co-ordinator of the Matrix and the Doctor's teacher. (PDA: Divided Loyalties)

At some point during the Doctor's fourth incarnation, the Doctor and Azmael had an encounter in which Azmael had drunk so much that the Doctor had to throw him into a pool to get him sober.

When Mestor, who commanded the Gastropods, came to power on Jaconda, he used a telepathic link with Azmael to dominate his mind. Under the guise of Professor Edgeworth, the villainous Mestor forced Azmael to kidnap the two young genius identical twins, Romulus and Remus Sylvest. By this time, Azmael had reached the end of his regenerations.

Recently regenerated himself, the the Doctor, Peri and Hugo Lang come to Jaconda by happenstance, the Doctor recognized Azmael as a friend from their homeworld of Gallifrey. Cooperating with Mestor, in order to save his people, Azmael abandoned the Doctor and Peri resulting in them being taken captive. When Mestor took possession of Azmaels body and the Doctor destroyed Mestor's real body. Azmael, with Mestor's spirit within him, then forced himself to die by inducing a last regeneration. This caused the death of both Azmael and Mestor. (DW: The Twin Dilemma)