Simon Montacute (died 1345) was a medieval Bishop of Worcester and Bishop of Ely. Montacute was the third son of William Montagu, 2nd Baron Montagu (d. 18 October 1319), by Elizabeth Montfort (d. August 1354), daughter of Sir Piers Montfort of Beaudesert, Warwickshire. He had two elder brothers, John, who died in August 1317, and William Montagu, 1st Earl of Salisbury, and a younger brother, Edward Montagu, 1st Baron Montagu, who married Alice of Norfolk, daughter of Thomas of Brotherton and granddaughter of Edward I. Among his seven sisters were Elizabeth, Prioress of Halliwell, and Maud and Isabel, successively Abbesses of Barking from 1341 to 1358.