Noko

Noko (changed to Dream in the anime) is the main antagonist of the Ocean's Dream filler arc (based off the video game of the same name) of the anime One Piece.

When the Straw Hat Pirates dock outside his home island for the night, he steals the memories of the entire crew (except for Robin because she was awake). When Nami and Zoro, not remembering anything, go off on their own, Noko uses his Devil Fruit powers to hypnotize Zoro into wanting to fight and defeat his captain, Monkey D. Luffy. It buys him enough time to locate the rest of the crew and steal the rest of their memories until Sanji kicks him down. Noko then comes out of a hypnotic state, causing the crew to realize that it was actually his sea horse Tatsu that was stealing the memories. Noko runs away and back to his home village and, thinking the Straw Hats were the memory thieves, rallies the villagers to chase the pirates down.

Trivia

 * Despite eating a Devil Fruit, he is able to walk underwater in the anime
 * His name is never revealed until his mother sees him returning to the village towards the end