Hercules

Hercules is one of the primary characters featured in Kingdom Hearts, Kingdom Hearts: Chain of Memories and Kingdom Hearts II. He is a demi-god and son of Zeus, living in Olympus Coliseum. His enemy is Hades, lord of the Underworld. Hercules possesses great strength and can battle the toughest of monsters. He is very supportive of Sora's goal to become a true hero. Voiced by Sean Astin of Lord of the Rings fame in the first game, but his original voice, Tate Donovan, reprises his role in the second.

Kingdom Hearts II
''A legendary hero with super strength - and a pretty great fellow, too. Hercules is the son of the gods Zeus and Hera, but he's not a god himself. Not long ago, he joined forces with Sora and his friends to stop Hades from taking over the world.''

''Hercules really impresses the crowds when he battles in the Coliseum. He's never lost a match yet.''

Kingdom Hearts
"A legendary hero with godlike strength. He's the son of the gods Zeus and Hera, but not a god himself. The people regard Hercules as a true hero.  He went from "zero to hero" in "Hercules" (1997)

Kingdom Hearts
Hercules is not seen for a while in Olympus Coliseum until he saves Sora, Donald, Goofy and Cloud Strife from Cerberus. Sora, Donald and Goofy run back to battle Cerberus so Hercules can escape with an unconscious Cloud. Upon the defeat of Cerberus, Hercules is impressed with the trio but encourages them to continue training when Phil grants them "Junior Heroes". Hercules later battles Sora in a one-on-one battle in the Hercules Cup.

Kingdom Hearts II
Hercules spends most of his days in the coliseum battling Hades' monsters including the Rock Titan and the Hydra. He gets rather tired but hides his exhaustion from Megara and his friends. He later feels depressed for the destruction of the coliseum at the hands of the Hydra. Upon Sora's second visit to the destroyed Coliseum, Hades advises Hercules to regain his pride by fighting Auron in the Underdrome - to the death. Sora, Donald and Goofy stop the fight and help both Auron and Hercules to regain their strength. The group defeat Hades. The credits of the game show Hercules successfully has rebuilt the Coliseum all by himself.

Trivia
Hercules is the only Protagonist besides Sora, Donald, and Goofy to fight Final Fantasy heroes.