Chela was a Manussan historian and Ambril's assistant.
Unlike Ambril, Chela was convinced by the Fifth Doctor's warnings that the Mara was returning. He assisted him in finding Dojjen and learning how to defeat the Mara. When Lon reinstated the Great Crystal, Chela was one of the many who had their mental energy drained. When the Doctor broke the crystal, they were released. (TV: Snakedance)