Gemon is a giant pitch-black gryphon that's a recurring boss in the Dragon Quest series. He originated in Dragon Quest VIII where he invaded the Godbird's nest and took posession of her only egg to put her in check for his master Rhapthorne. He somewhat resembles Jamirus from Dragon Quest VI but it's pitch-black and twice its size.
In Dragon Quest Monsters Joker 2, he and Jamirus reside at the top of Cragravation and keep Melonie imprisoned. The scout hero and Captain Rex Mayday team up to take them down, the player having to fight Gemon as the boss. It can be synthesized with a Jamirus and aBelial.