Cedric (Search Out Space)

Cedric was a humanoid from the planet Quirk. He resembled a black-haired, dark-skinned, clean-shaven human man wearing metallic clothes, and his voice had a high-pitched, metallic distortion to it.

Biography
Hailed as the most intelligent inhabitant of the planet Quirk, Cedric took part in the contest show The Ultimate Challenge, with the Seventh Doctor as host, and Ace (a human) and K9 (a robot) as opponents. Throughout the game, Cedric proved reasonably clever, but on several occasions he made presumptions about the planet Earth (which he had never visited) which turned out to be flatly wrong. The first and most striking was his belief that the planet's shape was that of a cylinder rather than a sphere. (NOTVALID: Search Out Space)

Behind the scenes
The physical description of an unnamed companion in PROSE: The Blue Angel is very similar to that of Cedric.