Uther Pendragon

King  was the father of Arthur Pendragon.

His "Merlin", the title of the King's advisor, necromancer and bard, was Blaise. Arthur remembered him Blaise as a cunning and loyal advisor to his father. He died at the same time as Uther, so that Arthur had to choose The Master upon his coronation. (PROSE: The Creation of Camelot)

Uther fancied Igerna, the wife of Gorlois. While Gorlois was away fighting a battle, a hooded figure claiming to be a wizard called Merlin (and who was in actuality a Renegade Time Lord disguised Uther to look like Gorlois. He impregnated Igerna, who believed it was her husband. After it was learned that her husband had died during the battle, Uther married Igerna (PROSE: One Fateful Knight) and King Arthur, Igerna's son from her mysterious encounter with "Gorlois", was generally acknowledged as Arthur's father, giving him an eventual claim to the throne. (PROSE: The Creation of Camelot, Legends of Camelot)

According to one account, he also had an affair with Morgaine, an alien conqueror and sorceress, (PROSE: One Fateful Knight) who was an echo of the true Morgwen. (PROSE: Legends of Camelot) This affair produced Mordred. (PROSE: One Fateful Knight)

Behind the scenes
He was played by Anthony Head in the 2008 BBC Wales series.