C is for... Calib

A council member of the Sevateem tribe, who were descendants of an expedition from Earth which crashed onto a nameless planet generations ago. The tribe worshiped the god Xoanon, but Calib was rather cynical and scathing of their High Priest, Neeva. He wanted to take control, and would do anything to achieve this. Tribe member Leela saw him as distrustful and treacherous.
Calib was right not to believe in Xoanon. It was really the computer from their ship. The Doctor had encountered the expedition soon after the crash and fixed the computer using a mental link to his own mind. He hadn't realised that the computer was developing an intelligence of its own - resulting in it becoming unbalanced. It decided on a programme of eugenics, splitting the survivors in two. The Survey team became the Sevateem - living a natural, instinctive life in the wilderness - and the technicians who stayed behind on the ship became the Tesh - who lived an ascetic existence, with their minds artificially enhanced.
Calib was quick to accept what the Doctor was trying to tell the tribe, though he was prepared to attempt to kill Leela with a toxic Janis Thorn when she continually challenged him.
When tribal leader Andor was killed, Calib would have expected to take command - but it is more likely that the more trustworthy Tomas would have taken over, as the cured Xoanon sought to reconcile the two parties.

Played by: Leslie Schofield. Appearances: The Face of Evil (1977).

• Schofield and Louise Jameson (Leela) were reunited a few years later on Eastenders. 
• Between the filming at Ealing and the studio recordings, the rest of the cast decide to pronounce his name differently - Caalib becoming Caylib.
• He is one of that small but notable band of Doctor Who guest artistes who have played Imperial Officers in the Star Wars films. He's in the first one, last seen warning Darth Vader that the Rebel spaceships might be on to something in their attack on the Death Star.