Jaguar D. Saul

Japanese name:

ハグワール・D・サウロ

Former Vice Admiral Jaguar D. Saul is a giant who first appeared as a castaway on the island of Ohara. He was introduced in Nico Robin's flashback during the Enies Lobby Arc, and by then he had already defected from the Marines.

http://onepiece.wikia.com/wiki/Jaguar_D._Saul