Brereton, William (c.1485–1541), soldier and lord justice of Ireland, was of a gentry family from Chester. He was knighted at Tournai, Flanders (1513), and seems to have spent much of his career in Cheshire and to have had no connection with Ireland before being sent there during the rebellion of Silken Thomas (Thomas FitzGerald (qv), 10th earl of Kildare). Brereton was ordered to muster troops at Chester in September 1534 and sail for Ireland, but waited for the deputy, William Skeffington (qv). The expedition sailed in October 1534 and Brereton landed in Dublin with 500 men on 17 October. He was welcomed by the mayor of the city and was joined by Skeffington a week later. On 27 October 1534 Skeffington and Brereton marched north to Drogheda on the rumour that Kildare was about to besiege the town, but found no siege in progress. Brereton and his men were then garrisoned at Newcastle Lyons to guard the southern approaches to Dublin. In March 1535 his force killed a hundred of Kildare's men, and later in the month he took part in the capture of the Geraldine stronghold at Maynooth. He remained in Ireland as a member of the Irish council until the spring of 1536, when he returned to Chester and became the chamberlain for the county.
In October 1539 he was ordered to recruit 250 men and return to Ireland; although his ability to lead troops was curtailed when he broke his leg before going to Ireland, he was in Dublin by the end of the year. He was again a member of the Irish council and was elected by the council as lord justice, when the lord deputy, Leonard Grey (qv), was recalled; he was sworn in on 2 May 1540. As governor he attempted to deal with Grey's legacy, showing himself to be more willing than Grey to work with the council and more prepared to negotiate with Con Bacach O'Neill (qv) to secure a peace. He was well aware of the unsettled nature of Ireland at the time and seems to have encouraged the efforts of James Butler (qv), 9th earl of Ormond and Ossory, to restore communication with James fitz John FitzGerald (qv), 14th earl of Desmond, but was unable to come to terms with the O'Connors. When Sir Anthony St Leger (qv) became lord lieutenant in August 1540, Brereton was rewarded with the office of marshal of Ireland. He died sometime before 26 March 1541.