Halenald de Bidun or Halneth de Bidun was a Breton who held land in England during the reigns of King Henry I and Stephen. Halenald was from either Bidon or La Ville-Bidon, two locations in the Dol region of Brittany. By the late 1120s he was overlord of a group of manors around Lavendon in Buckinghamshire. The lands were held in 1086 by William, who was the chamberlain of Geoffrey de Montbray, the Bishop of Coutances, when they were recorded in the Domesday Book as William's. The historian I. J. Sanders considered the honour of Lavendon as probably an English feudal barony, which if true would make Halenald the .