Merlin

Merlin can be found on the top floor of the southeast tower. If the player has not completed the Merlin's Crystal quest, he will be imprisoned within a block-shaped crystal.

After successful completion of the Knight Waves Training Grounds, a player can speak to Merlin in order to change spawning point to Camelot instead of Falador or Lumbridge.

Trivia
Merlin, of course was based off the real thing.