Envy the Jealous.
One of the first Homunculi created by Father, speculated by fans to be the 3rd oldest under Pride and Lust. Envy is a character which can change outwards appearance and voice. Because of this, Envy does most of the Homunculi spy work. Fans debate over Envy's true gender. In the brotherhood series and original manga, all the characters call Envy "He and him" so for now, we'll come him a he.