William le Petit, Petyt, or Lepetit (died after 1360) was an Irish judge who was very briefly Lord Chief Justice of Ireland. He is chiefly notable for having been pardoned for homicide.
It is unclear if he had any connection to the Petit family, who had the title Baron Dunboyne. Sir William le Petit, of County Meath, who came to Ireland with Hugh de Lacy, was Justiciar of Ireland in 1191. in addition to the expenses they had incurred. In 1348 he and the Serjeant-at-law, Edmund of Barford, attended the session of Parliament held at Kilkenny, and were paid their expenses for attending.
He was a justice of the Court of King's Bench (Ireland) by 1347, and in 1359 briefly replaced John de Rednesse as Lord Chief Justice. Shortly afterwards he was appointed Deputy to the Justiciar of Ireland. ;ref name =Patent ;"Patent Roll 33 Edward III 14 October 1459" ;/ref ; The records refer to the inability of a single judge to cope with the volume of judicial business. Accordingly William, whose legal ability and loyalty were vouched for by his colleagues (including, it seems, John de Rednesse), was to have full authority to act as a judge in all the Royal Courts.
He had two powerful patrons in James Butler, 2nd Earl of Ormond, and his wife Elizabeth Darcy, who employed le Petit as her attorney. It was at their request that le Petit in 1351 received a royal pardon for killing Robert de Lynham; little is known of the circumstances of the crime.
References.
 ;templatestyles src="Reflist/styles.css" / ;