Uther Pendragon is the father of King Arthur and his predecessor as king.
The name "Uther Pendragon" (or a variation) appears in a few early Welsh poems, but it is not until Geoffrey of Monmouth's History of the Kings of Britain (Historia regum Britanniae) that the name is used explicitly to denote Arthur's father. Geoffrey's account of Uther's life story and, in particular, his begetting of Arthur upon Ygerne, the wife of his vassal Gorlois, the Duke of Cornwall with the assistance of Merlin's magics is adopted by nearly every subsequent medieval writer.
Anthony Head as Uther on Merlin (UK, 2008)
After giving up Arthur to be raised by Merlin, Uther died from poisoning along with most of his household and was greatly mourned for his years of firm but fair rule