Mikazuki (ミカズキ) was the pirate that Galley-La beat after being threatened by him. He is the captain and only known member of the Big Helmet Pirates. He wears a large spherical helmet similar to Kokoro's with a crescent moon on it and has large canines resembling a demon. He has a bounty of Belli36,000,000. He is later seen in the fillers working for the debt collectors but he is easily defeated by Zoro. His name is Japanese for "crescent moon".

Source: http://onepiece.wikia.com/wiki/Mikazuki