Merlin was a wizard in the Middle Ages who was a mentor and friend of King Arthur.
The Real Ghostbusters
Merlin imprisoned Sir Bruce and his knights in artwork. While not much is known about Merlin, it is clear that Sir Bruce fears him. Peter Venkman poses as Merlin to force Sir Bruce outside where he is vulnerable to daylight. The Ghostbusters trap him.
- "Hard Knight's Day"
- He is mentioned and Peter poses as him