Caesar Clown is a villain from One Piece. He is a scientist who has the power of the Gasu Gasu no Mi which has the power to manipulate gas. He used to be a subordinate of Donquixote Doflamingo and used to work alongside Monet and Vergo.
Caesar is a sadist who enjoys inhumane experiments. He considers himself the greatest scientist in the world and have envy towards Vegapunk who is considers a better scientist. Caesar shows signs of psychopathy and has no remorse for manipulating, torturing, and putting lives of the people of Punk Hazard in danger. While Caesar cares little for the lives of anyone around him, he values his life greatly and can become fearful of his life that is put in danger.
Caesar Clown has the power of the Gasu Gasu no Mi which allows him to manipulate gas and vapor. He can use his devil fruit ability to fly and become intangible to physical attacks by manipulating the gas in his body. He can use the gas to poison his targets who gets near him. With the ability of manipulate gas, Caesar can remove the oxygen from the area around him rendering his targets incapable of breathing. Caesar can use the gas around him to create and manipulate fire to burn his target. Caesar can wield a sword with a blade made of vapor to slash his targets at superhuman speed.
Though Caesar is intangible to any physical attack, users with Armament Haki can physical harm him such as Luffy. Caesar Clown cannot use any of his devil fruit abilities when he is shackled with seastone chains.