William of Kilkenny

William of Kilkenny (died 21 September 1256) was a Lord Chancellor of England and Bishop of Ely.

Life William may be the same William of Kilkenny who was elected Bishop of Ossory in 1231, but resigned the office in 1232 before being consecrated. Whether or not that was the case, the man who later became bishop of Ely was a king's clerk by 1234. He was sent to Rome on royal business twice, once in 1234–1235 and again in 1237. In 1238 he left royal service, and was employed by two successive bishops of Durham, Nicholas of Farnham and Richard Poore. By May 1247 he was back in royal service, for in that month King Henry III of England sent him overseas.

William was Archdeacon of Coventry, from November 1247,

William was elected to the see of Ely about 29 September 1254 in Spain where he had gone on a diplomatic mission for the king. His heart was sent to Ely for burial in Ely Cathedral. His only known relative was a nephew who held land in Waterford and was knighted in 1254.