Roronoa Zoro

History
Roronoa Zoro trained as a swordsman at a very young age at the Shimotsuki Village dojo, where he gained experience in the was of the sword. When his childhood friend Kuina died, he honored her legacy by inheriting her sword, and created his signature "Santoryu" which had him use three swords at once.

He went of to find  Dracule "Hawk-Eye" Mihawk, the best swordsman in the world so he could take the title from him, but was captured by a Marine Corp after saving a little girl form the Captains Son's dog. He would eventually meet Monkey D. Luffy, and after rescuing him, agreed to a part of Luffy's crew as Luffy's first mate.

One Minute Melee
Zoro appeared as a combatant in One Minute Melee, where he fought against Rurouni Kenshin from Samurai X and won.

Trivia

 * Zoro is the first One Piece character to appear in Death Battle.