Sir William Brabazon, KB of Sproxton, Leicestershire was an English politician who represented Leicestershire and Northamptonshire in Parliament.

He was descended from Matthew Brabazon, the younger brother and heir of the Chief Justice of the King's Bench Roger Brabazon.

William responded to King Edward I's call to arms to gather at Westminster and was knighted by Edward, the then Prince of Wales, in the Feast of the Swans at Westminster Abbey on 22 May 1306.

[3] Sir William sat in the Parliament of September 1313 for Leicestershire.

This article about a 14th-century member of the parliament of England is a stub.