Sir William Courtenay (1451–1512) of Powderham in Devon, was a Lancastrian loyal to Henry Tudor, the future King Henry VII.
Courtenay was the eldest son and heir of Sir William Courtenay (1428–1485) of Powderham and Margaret, daughter of William Bonville, Baron Chewton Mendip.
In about 1476 he married Cecily Cheney, daughter of Sir John Cheney of Pinhoe, by whom he had children including four sons:
He also had seven daughters: Elizabeth (born 1483), Anne (born 1485), Joan, Cecily, Eleanor (born 1493), Margaret, and one other.
Courtenay died in November 1512.