Roy Mustang/2003 Anime

Mustang makes his first appearance in the series in Episode 1, when the Elric brothers attempt to resurrect their mother Trisha. Subsequently, Mustang is formally introduced in Episode 3 after Alphonse brought Edward to the Rockbells' home.

His Role in the Story
As a lieutenant colonel in the State Military, Mustang came to the Elrics' hometown of Resembool in search of their father, Hohenheim. It is also implied that Roy was seeking out the Elrics' childhood friend Winry Rockbell, the girl he had orphaned during the Ishval Rebellion, in order to see how she was doing (Episode 16). Recognizing Edward and Alphonse's talent for alchemy, he offered them a chance to become State Alchemists and to seek him out at Central City, where he was currently stationed.

Although appearing in episode 1, the first time he speaks is in episode 3, albeit only a single sentence.

The Elrics take up his offer and he has them sent to live with Shou Tucker for the purpose of studying for their State Alchemy Exam, informing them of Tucker's previous feat of creating the first talking chimera 2 years earlier. While escorting the Elrics to Tucker's home, he forewarns them to be nice as Tucker has a young daughter. Edward reluctantly becomes Mustang's direct subordinate when he becomes a State Alchemist.

After Tucker transmutes his daughter Nina into a chimera and she is subsequently murdered by Scar, Mustang warns a devastated Ed that he won't be helping anyone by trying to revive her upon seeing him trying to transmute her bloody remains. He goes on to lecture Ed about how hopeless causes are to be expected for him to face on his and Al's chosen path and encourages Ed to move on with his life. To further enrage Ed, Mustang places him in charge of gathering up Tucker's research and refuses to involve him in the State Military's attempt to track down Barry the Chopper, after Ed temporarily resigns his commission. After Ed and Winry are saved from Barry by Al and Maes Hughes, Mustang allows Ed to search for the Philosopher's Stone when not on an assignment in exchange for him keeping the details of their Human Transmutation secret and gives Ed the title of Fullmetal Alchemist.

Mustang is transferred to the Eastern Territories to clean up Lieutenant Yoki's mess Episode 9 and is promoted to colonel. He remains at Eastern Headquarters for the early portions of the series until he is transferred back to Central after Hughes' death.

In Episode 15, it is revealed that Roy had executed Winry Rockbell's parents under Basque Grand's orders in place of Scar in the manga. He was devastated by his cold-blooded actions and tried to kill himself, but to Hughes, Edward, and his subordinates, Roy explains his failure to do so by saying that he "was too much of a coward" to pull the trigger. Instead, Roy decides that he is going to work to reach a position where he would not have to obey orders like that: becoming the Führer.

When Hughes dies, Mustang is devastated. When pursuing the Elrics after the Stone's creation in Reole, Mustang learns that the Führer is a Homunculus, and tries to expose him to the top brass of the military by revealing the truth about the Führer's secretary, Juliet Douglas in Episode 45. Once the Führer's reaction goes as Mustang planned, which also confirmed his suspicions, Mustang began to realize that the Homunculi were responsible for the Ishvalan Civil War to create the Philosopher's Stone. Because of this revelation, Mustang has now developed an intense hatred towards Bradley for the genocide the military committed under his rule.

After he and Major Armstrong are promoted one rank and sent to Drachma, although Bradley intends for him to die in combat during the Northern Campaign on the front lines, Mustang instead stays in Central, making his move to avenge Hughes' death. He explains his actions to Edward at the end of Episode 48, saying that he has given up his goal of becoming Führer to avenge Hughes, much like Edward had given up restoring Al with the Stone. He points out his and Ed's similarities in the scene, and Edward finally comes to respect and understand him. Roy then moves on to the Führer's mansion and stages his fight. In Episode 51, Mustang is only able to defeat King Bradley when Bradley's son, Selim, unwittingly brings the skull of the man from which the Führer was created and weakens Bradley. In a fit in rage, he snaps Selim's neck, killing him almost instantly.

As Mustang escapes the Führer's burning mansion, he is confronted by a maniacal Frank Archer, who shoots him leaving him face down in a pool of blood. Hawkeye arrives in time to save him and kills Archer.

It is then revealed that Roy loses an eye from being shot by Archer but retains an optimistic attitude. When Hawkeye despairs at him that she should have been there to stop Archer, Roy says that "the world's not perfect" and "that's what makes it so beautiful." He seems to not be unhappy with what transpired in the Führer's mansion, and that the loss of his eye only showed that "nothing is ever perfect."

Envy shape-shifts into him during Episode 50 in a failed attempt to guilt trip Ed into keeping him alive. When he does this, Ed laughs and shouts "You couldn't have picked an easier target!"

Conqueror of Shamballa
In Conqueror of Shamballa, the movie that concluded the storyline of the 2003 series, Mustang resigns from both alchemy and his rank to become an ordinary enlisted man in a remote outpost. The events of the series are shown to have taken a heavy toll on Roy, since he says he has not used his alchemy since killing Führer Bradley; Roy says that he can still see the people he had killed in Ishval with his blinded eye. However, when Central is under attack by armies and airships, Mustang steps up and takes command, using his alchemy to defend Central. Mustang and Armstrong are able to find a hot-air balloon to reach the airships, where he is reunited with the Elric brothers, and helps them gain entry into the airship. Roy is glad to see Edward alive and well, and it is implied that it is Roy seeing Edward again that galvanizes Roy into taking charge and giving orders and using his alchemy again. When Edward leaves, he is the one to hold Alphonse back but he lets Al go in order for the younger Elric to follow his older brother. At the end of the movie, Al says that Mustang and his team are now responsible for destroying the Amestris side of the Gate.