Devotee of Apeiron
From Tardis Wiki, the free Doctor Who reference
A Devotee of Apeiron was a member of a cult and religious order that existed within the ranks of the Time Lords of Gallifrey. The Architect was known to have been a member of this group though knowledge of this was kept secret amongst the Gallifreyans due to the superstition involved with being associated with such a cult at the time. (PROSE: The Ancestor Cell)
