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

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.

[1] William died on 21 September 1256,[4] in Spain where he had gone on a diplomatic mission for the king.

[1] He had constructed an elaborate tomb that remained empty, and is now located near the high altar in the north choir aisle of Ely Cathedral.