Ucy

Japanese name:

闘牛

Fighting Bull is a gladiator competing at the Corrida Colosseum. He is nicknamed Ucy by Luffy, and renowned in the Colosseum as the Brutal Bull. He is described by Gatz as the "Colosseum's Grim Reaper", and his fighting style has led him to become known as the "Brutal Bull". Despite this, Luffy was still able to tame and befriend him using his Haoshoku Haki.

The One Piece Wiki