Monkey D. Dragon is an infamous character from Luffy’s adventure in One Piece and one of the main antagonists. He is said to have a powerful Devil Fruit, but its exact nature is unknown.
It is speculated by some that he ate the Dragon-Dragon Fruit, as he is known to have incredible powers, including the ability to breathe fire. This would make him a Logia-type user, capable of transforming into a dragon.