Scar, also known as the Scarred Man, is a character defined by a deep-seated quest for vengeance against the state alchemists of Amestris. He is a survivor of the Ishvalan Civil War, a brutal conflict in which the military, including many state alchemists, devastated his homeland and its people. His real name is never revealed in the story, as he forsook it after the war, believing he no longer deserved the name his god had given him. His moniker comes directly from the prominent X-shaped scar that marks his forehead, a permanent reminder of the violence that reshaped his life.

Before the war, Scar was a warrior monk in training, dedicated to his faith and the traditional martial arts of his people. His life changed forever thanks to his older brother, a brilliant but prohibited researcher of alchemy, a practice considered blasphemous by the Ishvalan religion. During the final, most savage days of the war, Scar and his brother were attacked by the state alchemist Solf J. Kimblee. In the attack, Scar lost his right arm and received the scar on his face. His dying brother used his own alchemical knowledge to perform a desperate transmutation, severing his own right arm and attaching it to Scar's body. This new arm came pre-marked with a distinctive, tattooed transmutation circle. This act saved Scar's life but also connected him forever to the alchemy he despised.

Following the war, Scar was taken to a field hospital run by the Rockbell doctors, Yuriy and Sarah. Upon waking and realizing where he was, he was overcome with grief and rage. Viewing the Amestrian doctors as an extension of the enemy that destroyed his people, he murdered them, a sin he would carry with him for the rest of his life. This event set him on his path as a wandering killer. After years of tribulation, he interpreted a chance encounter with a suffering chimera as a divine sign, deciding to use the destructive power now in his right arm to systematically hunt and kill all state alchemists as an act of holy retribution.

Scar's personality is shaped by tragedy and a rigid moral code twisted by trauma. He is typically stoic, serious, and quietly intense, but this calm can instantly erupt into explosive fury when confronted with a state alchemist or a reminder of the war. Despite his murderous mission, he is not without principles. He shows empathy for victims of alchemical hubris, such as the chimera Nina Tucker, whom he kills as an act of mercy. He is initially surprised and conflicted by the bond between the Elric brothers, Edward and Alphonse, as their loyalty to one another reminds him of the brother he lost. His worldview is that alchemy is a sin that arrogantly attempts to reshape God's creation, and he sees his use of alchemy only for destruction as somehow less offensive because he stops short of the reconstructive step. This internal conflict is a core part of his character; he never fully reconciles using his brother's gift with his own faith, often feeling he is a sinner compelled by a force he cannot control.

Scar's role in the story is that of a formidable and relentless antagonist for the Elric brothers during the first part of the narrative. He serves as a physical threat and a moral foil to Edward, challenging the boy's commitment to being a state alchemist. His primary motivation is revenge against the military and the alchemists who enacted the genocide of his people. However, as he learns more about the homunculi and the conspiracy at the heart of the Amestrian military, his motivation shifts from simple vengeance to a broader fight against those who truly orchestrated the suffering of Ishval. He eventually becomes a reluctant ally to Edward and others, joining forces to stop the homunculus Father and his plan to sacrifice the entire nation.

Key relationships significantly shape his development. His deceased older brother is the most important figure in his life, whose sacrifice haunts and empowers Scar throughout the story. His hatred for state alchemists is personified in Solf J. Kimblee, the man who killed his brother and scarred him. His murder of Winry Rockbell's parents creates a deep, tragic connection to her, one that forces him to confront the cyclical nature of revenge when Winry has the chance to kill him but chooses not to. His interactions with the Elric brothers, Alphonse in particular, soften his hatred and force him to see the humanity in those who practice alchemy. This is especially true as he witnesses their refusal to use human sacrifices and their commitment to protecting others.

Scar undergoes a profound development from an obsessive serial killer to a man who chooses to protect rather than simply destroy. The turning point is learning the full truth: that the Ishvalan war was deliberately engineered by the homunculi to create a Philosopher's Stone. This revelation redirects his anger from state alchemists as a whole to the true architects of the genocide. He eventually completes his character arc by embracing the "reconstruction" step of alchemy, having his left arm tattooed with a new circle that allows him to create and repair. This act represents him finally accepting his brother's gift in full and moving beyond pure destruction. In the final battle, he uses his abilities to help dismantle Father's nationwide transmutation circle and helps in the fight against King Bradley. After the conflict, he dedicates himself to the rebuilding of his nation, Ishval, completing his journey from an agent of death to a builder of a new future.

Scar's notable abilities center on his unique form of alchemy. His right arm, inherited from his brother, possesses a flash transmutation circle capable only of the first two steps of alchemy: comprehension and deconstruction. When he places his hand on an object or person, he can instantly analyze its material composition and then break the molecular bonds holding it together, effectively disintegrating it. This makes his touch a lethal weapon, as he can destroy a person's internal organs, turn a stone wall to dust, or shatter a weapon. He combines this power with his ferocious and highly disciplined martial arts skills as a former warrior monk, making him a devastating close-quarters combatant. Later in the story, after deciphering his brother's research, he acquires a reconstruction array tattooed on his left arm, which allows him to perform the third step of alchemy: reconstruction. This enables him to reshape matter, create barriers, repair structures, and perform complete transmutations, finally giving him the full alchemical power his brother intended.