Sir William Tresham JP (1404 – 22 September 1450) was an English lawyer and Speaker of the House of Commons. Born in Northamptonshire, the son of Thomas Tresham of Sywell, he went on to become a major landowner in the region. He was elected as a Knight of the shire for the parliament of 1423, and again in 1427, 1429, 1432, 1433, 1435, 1439, 1442, 1445, 1447 and February and November 1449, serving in twelve successive parliaments overall. In 1424 he was also appointed a Justice of the Peace for Northamptonshire; a man born of common stock relied on advancement in his home county for advancement nationally. Having trained as a lawyer, Tresham spent intermittent periods in the service of the king, such as in 1415, when he reviewed the accounts of the King's officials in southern Wales.