Uther Pendragon

Uther Pendragon (/ˈjuːθər pɛnˈdræɡən, ˈuːθər/;Welsh: Uthyr Pendragon, Uthyr Bendragon) also known as King Uther, is a legendary king of sub-Roman Britain and the father of King Arthur. A few minor references to Uther appear in Old Welsh poems, but his biography was first written down by Geoffrey of Monmouth in his Historia Regum Britanniae (History of the Kings of Britain), and Geoffrey's account of the character was used in most later versions.

He is a fairly ambiguous individual throughout the literature, but is described as a strong king and a defender of the people. According to Arthurian Legend, Merlin magically disguises Uther to look like his enemy Gorlois, enabling Uther to sleep with Gorlois' wife Lady Igraine. Thus Arthur, "the once and future king," is an illegitimate child (though later legend, as found in Malory, emphasizes that the conception occurred after Gorlois's death and that he was legitimated by Uther's subsequent marriage to Igraine). This act of conception occurs the very night that Uther's troops dispatch Gorlois. This theme of illegitimate conception is repeated in Arthur's siring of Mordred by his own half-sister Morgause in the later prose romances. It is Mordred who mortally wounds King Arthur in the Battle of Camlann.

...
Wikipedia