Trafalgar D. Water Law

Trafalgar Law is a pirate captain and doctor. He is one of eleven pirates who have been referred to as "The Eleven Supernovas" on Sabaody Archipelago whose bounties are higher than  100,000,000 when the Straw Hats arrive in the place. Not much is currently known about him other than the fact that he appears to be very laidback, as he was first seen sitting ontop of a crate as another pirate with a high bounty passed by, X Drake. He then asked how many did the latter slain. As for his weapon, he carries a katana with a hilt decorated with crosses from the opening to the bottom

Later, after Eustass Kid mentioned that he is mannerless, Law replies by flipping his middle finger up - a noteworthy feat, since Kid and his crew were several feet away from where Law was sitting when the Kid Pirates spoke behind the back of the Captain of the Heart Pirates. He was sitting next to a bear like creature.