Sir William Pennyman (1607 – 22 August 1643) was an English landowner, soldier and politician. He was the illegitimate son of William Pennyman (died 1628) a Clerk in Chancery and was educated at Christ Church, Oxford and Inner Temple. His father purchased a third of the Manor of Marske, Yorkshire, in present-day Redcar and Cleveland, in 1616. Pennyman later married Ann Atherton, granddaughter of John Atherton and Katherine Conyers and heiress to the remaining two thirds. His wife was also the granddaughter of Sir John Byron, whose daughter Ann married into the Atherton's.