For 10  points, name this man who fathered Galahad and had an affair with Guinevere, considered the best knight in the world.
This man was once imprisoned by three queens until he promised to marry one of them, but he was rescued by the daughter of his friend King Baudemagus. He suffered from madness for two years after being discovered in bed with Elaine of Carbonek, the daughter of the Fisher King. This half-brother of Sir Hector-de-Maris was responsible for the deaths of Gawain's brothers while attempting to rescue his lover from being burned at the stake. He had earlier saved that lover from Meleagant in an adventure that earned him the nickname "Knight of the Cart." For 10  points, name this man who fathered Galahad and had an affair with Guinevere, considered the best knight in the world.
This man was once imprisoned by three queens until he promised to marry one of them, but he was rescued by the daughter of his friend King Baudemagus.
Sir Launcelot