Envy, known in Japanese as Envī, is a homunculus and a major antagonist in Fullmetal Alchemist. As the physical embodiment of the sin of envy, this character represents the deep-seated resentment towards humans and their ability to form meaningful connections. Envy is one of the seven homunculi created by the being known as Father, making all the other homunculi siblings in a sense, with Father himself as the creator.

In terms of appearance, Envy's default form is that of an androgynous teenager with a slender build and sharp, almost effeminate facial features. The most distinctive physical trait is the long, dark green hair styled to resemble the fronds of a palm tree, which gives the character a very recognizable silhouette. The Ouroboros tattoo, the mark of a homunculus, is located on the outside of the left thigh. The androgynous design is intentional, making the character's gender ambiguous throughout most of the series, though the character is referred to with male pronouns.

The core of Envy's personality is a profound and all-consuming cruelty. This homunculus is one of the most sadistic and ruthless characters in the series, displaying a complete lack of remorse for any action, no matter how heinous. Envy takes genuine pleasure in the suffering of others and enjoys mocking human misery, often bragging about orchestrating catastrophic events, such as the Ishval Civil War, seemingly just for entertainment. Envy delights in playing with human emotions before delivering a final blow, typically by transforming into a victim's loved one to exploit their hesitation. The most infamous example of this tactic is the murder of Maes Hughes, where Envy assumed the form of his wife, Gracia, knowing the loving father and husband would be unable to fight back. Envy's defining flaw is a short temper and a tendency to become easily irritated, which often leads to reckless decisions and strategic errors during fights.

The primary driving motivation for Envy is an intense hatred for humanity. This hatred stems from a fundamental inability to understand or possess the qualities that humans take for granted, such as friendship, loyalty, and the inner strength to persevere through adversity. Envy views these human bonds as a profound weakness, yet there is a deep-seated jealousy that humans can achieve what a homunculus cannot. This internal contradiction defines the character, as the actions are all aimed at proving human inferiority to mask this painful truth. The driving force is to mock and destroy anything that highlights what Envy lacks.

Within the story, Envy serves as a primary agent of chaos and a recurring high-level threat for the Elric brothers. The shapeshifting ability is used extensively for espionage, infiltration, and assassination, making Envy one of Father's most versatile and dangerous tools. A key role is to act as a catalyst for other characters, most notably by being directly responsible for the death of Maes Hughes, an event that has lasting repercussions on the protagonists, especially Roy Mustang.

Envy has a complex and antagonistic relationship with several characters. The relationship with Roy Mustang is one of pure hatred, as Mustang seeks revenge for Hughes's death, leading to one of the most brutal confrontations in the series. The relationship with the Elric brothers, particularly Edward, is more philosophical. Through their battles, Edward forces Envy to confront the hypocrisy of looking down on humans. The key relationship is with Father, the creator, to whom Envy is utterly devoted but from whom Envy also seeks approval, highlighting a dependent and hierarchical dynamic among the homunculi.

The character undergoes significant development, culminating in a psychological breakdown. Despite immense power, Envy is ultimately defeated not by physical force alone but by being forced to acknowledge the truth of the human condition. Edward Elric points out that Envy, for all the boasting, is actually the one who is pitiful. The ability to rely on others, to admit weakness, and to forgive is a strength Envy can never possess. This realization is too much for the prideful homunculus to bear. In a final, ironic act that mirrors the self-destructive nature of envy itself, Envy takes the character's own life, destroying the philosophical core to escape the unbearable shame and jealousy.

The most notable ability is the power to shapeshift into any person, perfectly mimicking not only their appearance but also their voice. This power is used for deception, psychological warfare, and assassination. In addition to human forms, Envy can also transform into a massive, terrifying true form. This monstrous body, sometimes referred to as a dragon-like creature, is a giant, writhing mass of faces and limbs that grants immense physical strength, speed, and durability in combat. Like all homunculi, Envy also possesses rapid regenerative abilities fueled by a Philosopher's Stone, making the character incredibly difficult to kill through conventional means.