Jack is a leading member of Beasts Pirates and is one of the three beings called "The Calamaties" under the yonko Kaidou. He is also the commander of his own ship "Mammoth." Jack is shown to be very ruthless, fearless and has a very violent personality. He refuses to solve any matter through talking and would attack anyone, even his own subordinates, if they were to fail, without mercy. In his own words, he loves destruction. Jack is man of massive standing and is an Ancient zoan type devil fruit user. He ate the Zou Zou no Mi, Model: Mammoth. Jack has a bounty of 1,000,000,000 Beli.