Fullmetal Alchemist (Japanese: 鋼の錬金術師, Hepburn: Hagane no Renkinjutsushi) is a Japanese anime television series loosely based on the manga series Fullmetal Alchemist by Hiromu Arakawa. It was produced by Bones for Mainichi Broadcasting System and Aniplex. The series was directed by Seiji Mizushima, written by Shō Aikawa, and musically composed by Michiru Ōshima.

The anime series aired a total of 51 episodes on MBS, TBS and its affiliates from October 2003 to October 2004. It was originally licensed in North America by Funimation and broadcast English dubbed on Adult Swim in the United States from November 2004 to March 2006. In July 2016, Funimation's license for the series expired and it was transferred over to Aniplex of America.

Just like in the manga, the anime series follows the adventures of brothers Edward and Alphonse Elric, who are searching for the Philosopher's Stone so they can regain the bodies they lost in a failed attempt to bring their deceased mother back to life. During production of the anime, Arakawa requested a screenwriter-led original ending for the series that differed from the manga, which was still being actively published at the time. This led to the anime deviating into an entirely original story direction around the first dozen episodes. The anime's storyline concluded with a sequel film, subtitled Conqueror of Shamballa, which released in Japanese theaters in July 2005. An anime television series reboot, titled Fullmetal Alchemist: Brotherhood, broadcast on the same original networks from April 2009 to July 2010.

The first half of the anime's plot adapts the first six volumes of the manga, while the second half incorporates plot points from the seventh and eighth volumes with significant recontextualizations.

Dante, a former lover of Hohenheim, the Elric brothers' father, and mentor to the boys' teacher, is the series' main antagonist. Centuries ago, Hohenheim and Dante perfected methods for making the Philosopher's Stone and achieved immortality by transferring their souls and intellects into other bodies as they age. Hohenheim was eventually overcome with the guilt of sacrificing lives to make the Stone and left Dante. Although Dante can still jump from body to body with the last stone she and Hohenheim created, she is not willing to risk the rebound of creating one herself. She thus uses the homunculi to encourage Edward and Alphonse, along with other equally desperate Alchemists to create another complete Philosopher's Stone for her.

When Scar creates the Philosopher's Stone, at the cost of his life as well as the lives of 7,000 soldiers, he infuses it into Alphonse's metal body, which leads to Alphonse's kidnapping. Edward tries to rescue him, but is killed by Envy. However, Alphonse uses the Philosopher's Stone to revive his brother but disappears in the process, along with Envy, who fails to stop him. Dante tries to escape, but she is killed when the homunculus Gluttony, whose mind she had earlier destroyed, fails to recognize his master. After being revived, Edward risks his life to bring back his brother and finds himself in Munich, while Alphonse recovers his original body. Determined to reunite with Alphonse, Edward becomes involved in rocketry research, intending to use that technology to return to his home world. The story concludes in the film adaptation Conqueror of Shamballa, in which Edward's search attracts the attention of the Thule Society, which seeks to enter his homeworld—believing it to be Shamballa—to obtain new weapons to help them in World War II. Dietlinde Eckhart, a member of the Thule Society, enters the other world and tries to destroy Amestris. She is defeated by the Elric brothers, who decide to stay in Germany.

Bones president Masahiko Minami decided to create an adaptation of Fullmetal Alchemist after Bones staffers, including Yoshiyuki Ito, brought it to his attention. Bones subsequently secured a deal with author Hiromu Arakawa and publisher Square Enix to produce an anime adaptation.

During the development of the Fullmetal Alchemist anime, Arakawa allowed Bones to work independently from her, and requested they produce an original ending different from that of the then ongoing manga. She did not want to repeat the same ending in both media, and wanted to continue writing the manga to develop the characters at her own pace. When watching the anime's ending, Arakawa stated that she was amazed about how different the homunculi creatures were from her manga and enjoyed how the staff speculated about the origins of the villains. Although she was not fully involved in all aspects of the 2003 series, she was directly involved in the production of it at a storywise standpoint. As shown in the extras of Volume 8 of the manga, she helped the anime's development team with consultation for the characters and telling the overall story she had planned for her manga, helping them fill in some of the gaps to create the anime original ending of the 2003 series. Because Arakawa was involved in the development of the anime, she was kept from focusing on the manga's cover illustrations and had little time to illustrate them.