William ap Thomas

Sir William ap Thomas (died 1445) was a Welsh nobleman, politician, knight, and courtier. He was a member of the Welsh gentry family that came to be known as the Herbert family through his son William Herbert, 1st Earl of Pembroke (8th creation) and is the agnatic ancestor, via an illegitimate descendant of the 1st Earl of the 8th creation, of the current Herbert family of the Earl of Pembroke and Montgomery, and also of the Herbert Earl of Carnarvon.