Angus MacKay

Angus MacKay (15 July 1926-8 June 2013 ) appeared in two Doctor Who television stories: as Borusa in The Deadly Assassin; and Brendon Public School's headmaster Mr. Sellick in Mawdryn Undead, the latter of which saw him briefly portray the Black Guardian when he took on Sellick's appearance in a dream sequence.