William FitzWilliam (Lord Deputy) William FitzWilliam (Lord Deputy) Sir William FitzWilliam (1526–1599) was an English Lord Justice of Ireland and afterwards Lord Deputy of Ireland. In 1587, as Governor of Fotheringhay Castle, he supervised the execution of the death sentence on Mary, Queen of Scots. He was the Member of Parliament for Peterborough and represented County Carlow in the Irish House of Commons. He lived at Gainspark, Essex, and Milton Hall. FitzWilliam was born at Milton Hall, Northamptonshire, the eldest son of Sir William (d. 1576) and grandson of William Fitzwilliam, Sheriff of London, who had been treasurer and chamberlain to Cardinal Wolsey and
Valentine Dale treason. On 22 March following he was presented to the mastership of Sherburn Hospital, County Durham. His name occurs in the special commission for Middlesex (5 September 1586), under which Anthony Babington and others were indicted for treason. He assisted at the trial of Mary, Queen of Scots, at Fotheringhay, in October the same year; and to the parliament which met on the 15th of that month he was again returned for Chichester. He acted as one of the high commissioners for causes ecclesiastical at the deprivation of Robert Cawdrey on 30 May 1587. In February 1588 Dale, Henry Stanley,