Gluttony is the second homunculus to appear in the series, typically being in the company of Lust. He is a large, simple-minded homunculus whose thoughts rarely stray far from eating. He has powerful jaws, acidic saliva, and can and will eat almost anything. He particularly likes eating people, and the only way he can find enjoyment in a battle is if he believes he can eat his opponent afterwards. A running gag in the manga and anime is asking Lust (or any other Homunculi) if he can eat someone. He apparently prefers girls (as in to eat) and also seems to share a bond with his partner Lust.
There is no significant information pertaining to his role in the 2003 anime series.
In the manga and 2009 anime series
Gluttony is the sixth Homunculus created by Father...
(Source: Fullmetal Alchemist Wikia)