A god gone mad?

Tags: Fourth Doctor, Leela

The Face of Evil, episode 3
15 January 1977

Xoanon - worshipped as a god by the tribe of the Sevateem and their enemies the Tesh. As the Doctor’s recollections of an earlier adventure surface, he realises that the two tribes are the descendants of an expeditionary mission, and that Xoanon is a highly advanced computer, allowed to think for itself...