Renegade Knight

Renegade Knights are knights devoted to serving the evil sorceress Morgan Le Faye. They imprisoned the Knights of the Round Table and Merlin during King's Ransom. They can be accessed by taking the crate behind the candle shop in Catherby after the quest Merlin's Crystal.

Trivia

 * They appear to be wearing a different version of the Varrock guards' uniform. They are equipped with a dark variant of the helm and sash (around the waist), as well as wielding a similar short-sword.
 * During the King's Ransom quest, if you talk to Sir Lancelot while he is fighting the Renegade Knights, a Renegade Knight will plead for mercy in the conversation.