The protagonist of this story. A boy with refined features who, at first glance, appears to be an intellectual, honest, and sincere scholar type. Belonging to the Defense Force Weapon Development Lab in Colony 9, he researches the mysterious sword, the Monado, while also developing weapons by imitating his mentor, Dickson. He is generally mild-mannered and dislikes conflict, but possesses an inner bravery to face any enemy without fear. He sets out on a journey with his childhood friend Reyn to defeat the Mechon that attacked his hometown. He is a scholar at heart with an insatiable thirst for technical knowledge, and is somewhat poor at physical activity. That said, as a member of the military who has undergone standard training, he moves surprisingly well in combat. He loves tinkering with machines but hates caterpillars and vegetables. According to Dunban, he also seems to be a picky eater. He has a tendency to bottle up his worries and suffering, which often causes his companions to worry about him. Childhood friends with Fiora and Reyn. He uses the Monado as his weapon.

A Homs youth belonging to the Colony 9 Defense Force. He is childhood friends with Shulk and Fiora, and is particularly close to Shulk as his best friend. A large, muscular young man, he is a tough and reliable warrior just as he looks. He sets out on a journey with Shulk to defeat the Black Face that attacked Colony 9. In battle, he uses a "Bunker," a shield with a blade attached to the tip.

The younger sister of the Homs hero Dunban, she devotedly cares for him as he heals from his battle wounds. Her parents died in a Mechon attack when she was young. She also looks after her childhood friends Shulk and Reyn, who have no family. Because of this, she is much more mature mentally than her actual age and often takes the initiative in taking action. In fact, Shulk and the others are often swept along by the proactive Fiora. She is also an apprentice member of the Colony 9 Defense Force and fights bravely wielding daggers. During her enlistment test, her strength made the Defense Force eager to recruit her. She often cooks for everyone. She likes vegetables but dislikes delicacies and spicy food. She shows affection for small animals but tends to dislike insects. Childhood friends with Shulk and Reyn. She calls Dunban "Big Brother."

A hero who wielded the Monado in the great war against the Mechon one year ago and protected Bionis. At that time, he was injured and recuperating because he could not fully control the Monado's immense power, but he rushed to help during the Black Face attack on Colony 6 and has traveled with Shulk and the others since. Though hailed as a hero by those around him, he never puts on airs and remains consistently aloof. He appears calm for his age, but at his core, he is a bellicose, hot-blooded man. He feels no jealousy toward Shulk, who masters the Monado better than he ever did, and instead relies on him. He deeply cherishes Fiora, his only family, as her older brother. He gets along well with Riki, perhaps because they are fellow elders, and they often trade quips. Since he can no longer move his right arm properly, he has switched to a style of fighting that involves carrying a weapon (a katana) in his left arm and incorporating martial arts.

A Homs woman who served as a medic in the Colony 6 Defense Force. When Colony 6 was attacked by the Mechon, she escaped on an evacuation ship with her younger brother Juju and those unable to fight under orders from Otharon, the Defense Force Captain. They set up camp on the Bionis' Leg and lived in hiding. She is concerned about her fiancé Gadolt, who stayed behind to fight, and joins Shulk's journey to find him, believing he might be alive somewhere. In combat, she fights with an ether rifle she was trained on by Gadolt.

The crown princess of the "High Entia," a race living in the upper regions of Bionis. She speaks in a formal, archaic, and highly intellectual register. Her hairstyle is characterized by unique twin-tails with rolled sideburns. The High Entia royal family has a tradition of taking a Homs "Second Consort" to dilute the High Entia blood for various reasons. As the daughter of a Second Consort, Melia is half-Homs. Consequently, her features and height are closer to a Homs, and the wings on her head are about a quarter of the usual size. She is an ether-attribute supporter and attacker. Simply put, she is a mage.

A member of the Nopon race living in Frontier Village. His speech and behavior are extremely childish, even for a Nopon. For a certain reason, he has incurred a massive debt to the village and is forced to accompany Shulk and the others as this year's "Heropon." In addition to attacking with a mysterious blunt weapon, he has many Arts that cause status ailments using ether-"like" techniques. Despite the aforementioned childish way of speaking, Riki has a wife and eleven children. He apparently fell into debt because his children are big eaters (Nopons are naturally heavy eaters, but in Riki's case, the sheer number of people makes food expenses even higher), and he was made a hero to pay it back. Because of this background, Riki is actually the most mentally mature member of Shulk's group, contrary to his tone. He ends his sentences with "-mo."

Autonomous mobile weapons without a sense of self. They possess rigid armor that cannot be scratched by ordinary weapons, along with overwhelming power that surpasses Homs. However, their armor becomes neutralized if their balance is broken. Since their joints are depicted as relatively weak, one might target them during a Topple. Also, because they have little resistance to ether, they can be damaged by ether attacks or high-temperature ether flows.