William Devereux was an Anglo-Norman nobleman living during the reigns of kings William I, William II, and Henry I of England. The Devereux, along with the Baskervilles and Pichards, were prominent knightly families along the Welsh marches at the beginning of the twelfth century, and linked to the Braose and Lacy lordships of the region. William Devereux's descendants would later give rise to the Devereux family of Hereford, and the Devereux Viscounts of Hereford and Earls of Essex.