Who is Bill Rincewind from The Last Continent: A Discworld Novel and what is their importance?

Bill Rincewind is the archchancellor of BU, a school for wizards located in the capital city of the last continent, Fourecks, Bill Rincewind is a distant relative of the protagonist, Rincewind the Wizzard. When the Archchancellor of Unseen University (UU) on Ankh-Morpork meets him, he treats Bill as a decidedly inferior wizard and administrator, pronouncing his title in such a way as to indicate it is written without a capital letter.