Caesar Clown, also referred to as "Master" by his underlings, is the main antagonist of the Punk Hazard Arc in the anime and manga One Piece. He is a former colleague of Vegapunk, Vinsmoke Judge and Queen as well the leading scientist expert on mass-murder weapons with a bounty of 300,000,000 berries on his head.
He’s currently been kidnapped by the Strawhat Pirates and Law, in exchange for him Doflamingo has to lose his spot as a warlord, causing him to lose his throne in Dressrosa.