Jack Hanma (ジャック 範馬, Jakku Hanma) is a fictional character from the Baki the Grappler series. He's a pitfighter from Canada and the son of Yuujirou Hanma and Diane Neil, a Canadian United Nations operative who Yuujirou met during the Vietnam War. Like his brother, Baki Hanma, he has since childhood wished to surpass his father in strength and martial ability. In the English dub of the second anime series, his name has been changed to Jack Xamma because of dub issues (pronounced "Zah-mah").
His ringname is Jack Hammer (ジャック・ハンマー, Jakku Hanmā). In the fifth manga series, he is also known as the "Biting Cyborg" (噛みつき サイボーグ, Kamitsuki Saibōgu).