Original: Sir Lancelot (or Launcelot) du Lac (,,, or; and or) is one of the Knights of the Round Table in the Arthurian legend. He is typically considered to be one of the greatest and most trusted of King Arthur's knights and plays a part in many of Arthur's victories.
Simplified: Sir Lancelot of the Lake was one of the most trusted knights of King Arthur's Round Table, but this soon changed when he fell in love with the king's wife, Queen Guinevere.