Joke

Captain Joke was the main antagonist of the first TV special, "Adventure in the Ocean's Navel".

Abilities and Powers
Joke seems to have the ability to project mental images into the minds of others, as shown when he made Hamu witness the death of his mother at Joke's hand.

Weapons
Joke wields a revolver with a gatling gun-like barrel that can fire multiple rounds at once. The bullets explode on impact similar to Usopp's Kayaku Boshi.

History
Joke is a pirate captain who was after a treasure that allowed the holder to wish for anything they wanted. However, as he closed in on the treasure, his crew mutinied and viciously stabbed him in the back several times. However, for some reason he was turned into a bat and stayed in his body's remains, where he waited for ten years.

After this time, the Straw Hat Pirates came along and unknowingly killed all the monsters holding Joke's other bones as he guides them to the treasure. The bones are then returned to his body upon their defeat, allowing him to revive and continue to look for the treasure. He is stopped by Hamu, the son of a chief elder that Joke killed. The Straw Hats (Luffy, Nami and Usopp) hold him down to keep him from shooting Hamu with his multi-barrel pistol.

As Joke crumbles to dust, he comments he wishes he had a crew like them.