The Battle of Clyst Heath (1455) was a private battle fought on 15 December 1455 at Clyst Heath, now a suburb to the south east of Exeter in Devon. During the Wars of the Roses the mortal enemies of the Courtenay Earls of Devon of Tiverton Castle and Colcombe Castle were the Bonville family of Shute. The earl's cousin Sir Philip Courtenay (d.1463) of Powderham Castle however sided against him with Bonville and his son Sir William Courtenay (d.1485) of Powderham married Margaret Bonville, daughter of William Bonville, 1st Baron Bonville (1392–1461), which confirmed Powderham as a Bonville stronghold against the Earls of Devon. The prelude to the battle seems to have been the notorious murder on 23 October 1455 of Nicholas Radford, lawyer to Bonville, at his home at Upcott in the parish of C