Sir William Tresham JP (1404 – 22 September 1450) was an English lawyer who served as Speaker of the House of Commons until 1450.
Born in Northamptonshire, the son of Thomas Tresham of Sywell, he went on to become a major landowner in the region.
It is assumed he concentrated on his legal career in the 1420s, where there are few records of his activities, but in 1430 he was appointed as a councillor to Humphrey Stafford, 1st Duke of Buckingham, and continued to receive a salary until at least 1447.
He was again elected Speaker in 1442 and 1447 and continued his royal service, mainly for the Duchy of Lancaster, and worked as an Apprentice-at-law between 1444 and 1447.
In 1450 he was himself indicted for treason in the aftermath of Jack Cade's rebellion in Kent, but before any sort of commission could take place he was murdered.