Terra

Terra is a strong-hearted young man whose heart is pure, yet steeped in darkness. Troubled by the darkness that lurks inside him, he battles the Unversed and searches for Master Xehanort in an effort to learn to control and subdue his newfound “weakness”.

Terra grows close to Master Xehanort, who convinces him that the darkness within him is not a weakness, but an immense strength that Master Eraqus fears. Tempted by that power, Terra slowly succumbs to Master Xehanort’s will.
Ventus

Ven for short, Ventus is truly a gentle soul. Though he seems innocent and docile, his skills with the Keyblade are impressive, but his true power remains to be seen.

Coaxed by the mysterious Vanitas, Ven embarks on a journey to find Terra. His travels take him to many places and he meets many new friends along the way. Ven slowly uncovers the truth about the power within him, and discovers that he and Vanitas share a stronger connection than he ever realized.
Aqua

Aqua is a kind-hearted young woman, but she can hold her own in battle just fine. A loyal pupil under Master Eraqus, she follows orders to the letter.

Upon passing the Mark of Mastery exam, Aqua is sent with Terra to uncover the truth behind the mysterious Unversed and Master Xehanort’s disappearance. But when things become more grim than she could have ever imagined, it’s up to Aqua to conquer the darkness that threatens the worlds.
Master Eraqus

The Keyblade Master who took Terra, Ventus, and Aqua in as his pupils, Master Eraqus instills in his students that balance must be upheld between light and darkness at all times, and any threat to that balance must be dealt with.

When Ventus begins to uncover the truth about his power, Eraqus attempts to destroy that power by erasing him from existence. When Terra steps in to protect his friend, Eraqus reluctantly battles his surrogate son and the darkness he commands.

Master Xehanort

Another Keyblade Master, Xehanort is a curious old man with questionable intentions. His fascination with the legendary Keyblade War brings him to do truly terrible things to the worlds, and to Terra, Ventus, and Aqua.

Master Xehanort sees great potential in Terra and the dark powers he commands. Instead of advising him to suppress the darkness, he encourages him to use its powers to give him strength. Little does Terra know that Xehanort has a much more insidious plan in store for him.
Vanitas

A being of pure darkness extracted from Ventus’ heart, Vanitas is pure evil. He controls the lesser Unversed creatures as he releases them into each and every world. His obsession with making Ventus stronger comes from his quest for the power that would emerge if he and Ventus were to ever collide – the legendary χ-blade.

Vanitas works in league with Master Xehanort, as he too seeks the power of the χ-blade. The two of them cause trouble in numerous worlds in pursuit of their sinister goal.
Mickey

Mickey is the King of Disney Castle, training under Master Yen Sid in the ways of the Keyblade.  When Mickey senses danger brewing in the various worlds, he steals Master Yen Sid’s Star Shard to travel from world to world and help where he can.

Mickey’s journey leads him to cross paths with Terra, Ventus, and Aqua during their final battle against Master Xehanort at the Keyblade Graveyard.