Sir William Essex (1477–1548) was the High Sheriff and MP for Berkshire in England.
Sir William was the son of Thomas Essex of Lambourn in Berkshire and his wife, Elizabeth daughter of William Babthorpe of Elstone in Leicestershire. He married Elizabeth, daughter and heiress of Thomas Rogers of Beckett Hall in Shrivenham, also in Berkshire (now Oxfordshire). They had two children: Sir Thomas and Winifred. He served as High Sheriff of Berkshire and Oxfordshire in 1509, 1518, 1523 and 1540 and as one of the MPs for Berkshire in 1529–1536 and 1542–1544.