Bill Rincewind was Archchancellor of Bugarup University of EcksEcksEcksEcks. He appears briefly in The Last Continent. He is Rincewind's distant cousin. When the water disappeared on XXX due to the interference of the Unseen University wizards, he and the other wizards attempted to summon a demon to find out the cause, accidentally summoning Rincewind by mistake.
He is also mentioned in Unseen Academicals. Unseen University Archchancellor Ridcully does not mind Bill Rincewind calling himself Archchancellor as he is on another, very remote, continent. The rise of Brazeneck College in Pseudopolis, and the Dean calling himself 'Archchancellor' is quite a different matter. Rincewind and Ridcully correspond and send each other unpopular students as part of an exchange program. The parallels with long lost Australian relations (or other colonial descendants with British roots) visiting their ancestral homes and remote relatives are obvious.