The protagonist of this story. A handsome, honest, and sincere boy with the air of a scholar. Belonging to the Military District's Weapon Development Lab in Colony 9, he researches the mysterious sword, the Monado, while developing weapons by imitating his mentor, Dickson. He is generally mild-mannered and dislikes conflict, but possesses an inner bravery to face any foe without fear. He sets out on a journey with his childhood friend Reyn to defeat the Mechons that attacked his hometown. As a natural researcher, he is dedicated to technological inquiry and is somewhat poor at physical exercise. However, as a member of the military who has undergone basic training, he moves surprisingly well in combat. He loves tinkering with machines but hates caterpillars and vegetables. According to Dunban, he is also a picky eater. He tends to bottle up his worries and suffering, which often causes his friends 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 who lives up to his appearance. 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 were killed in a Mechon attack when she was young. She also looks after her childhood friends Shulk and Reyn, who have no family. Consequently, she is much more mature than her actual age and often takes the lead in getting things done. In fact, Shulk and the others are often swept along by the active Fiora. She is also a trainee in the Colony 9 Defense Force and fights bravely with 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 is fond of small animals but tends to dislike insects. Childhood friends with Shulk and Reyn. She calls Dunban "Big Brother."

The hero who wielded the Monado in the great war against the Mechons one year ago, protecting Bionis. At that time, he was injured because he could not fully control the Monado's immense power and was recuperating. However, he rushed to help when the Black Face attacked Colony 6 and has since traveled with Shulk and the others. Though hailed as a hero by those around him, he is never pretentious and always remains aloof and composed. He appears calm for his age, but at his core, he is a hot-blooded man who loves a good fight. He feels no jealousy toward Shulk, who masters the Monado better than he ever did, and instead relies on him. He deeply treasures Fiora, his only family, and has decided that if he were to marry his sister off, it would be to Shulk or Guest. He gets along well with Riki, perhaps because they are both older members of the group, and they often trade quips. Since he can no longer move his right arm properly, he has switched to a fighting style that involves carrying a weapon 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 Mechons, she escaped on a transport with her younger brother Juju and those unable to fight under the orders of Otharon, the defense chief. They set up camp on the Bionis' Leg and lived in hiding. She constantly worries about her fiancé Gadolt, who stayed behind to fight, and joins Shulk's journey to find him, believing he might still be alive somewhere. In battle, she fights with an ether rifle, having been trained by Gadolt.

The crown princess of the "High Entia" race living in the upper regions of Bionis. She speaks in a formal, archaic, and regal tone, often using complex vocabulary. Her hair is styled in a unique twin-tail fashion with rolled sideburns. Due to various circumstances, the High Entia royal family takes Homs concubines known as "Shadow Consorts" to dilute the High Entia bloodline over generations. As the daughter of a Shadow Consort, Melia is of mixed Homs descent. Consequently, her facial features and height are close to those of a Homs, and the wings on her head are about a quarter of the usual size. She is an ether-based supporter and attacker. Simply put, she is a mage.

A member of the Nopon race living in Frontier Village, located on the back of Bionis. 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. Because of his childish way of speaking, Shulk and the others initially thought he was a young Nopon, but Riki actually has a wife and eleven children. Because his children are big eaters (Nopons eat a lot to begin with, but in Riki's case, the sheer number of people makes food costs exorbitant), he fell into debt and was made a Hero to pay it off. Because of this background, Riki is actually the most mentally mature member of Shulk's group, despite his tone. He ends his sentences with "-pon."

Autonomous mobile weapons without a sense of self. They possess overwhelming power that surpasses Homs, along with sturdy armor that cannot be scratched by ordinary weapons. However, their armor becomes ineffective if their balance is toppled. Since their joints are depicted as relatively weak, one might aim for them while they are tripped. Furthermore, they have little resistance to ether, so they can be damaged by ether attacks or high-temperature ether flows.