He is a Vis with a large, fat head that has small, beady eyes.
Gluttony has 2 main attacks; an 8-way blood shot and a blood beam attack, similar to that used by Vis.
The room he appears in will always have the same setup, with Pits around him.
Gluttony is a relatively easy mini-boss, with only 2 attacks. His blood beam attack is very easy to predict and takes a long time to charge, so it can be avoided quite easily. Likewise, the "pop" attack, where he fires shots, can be avoided with ease so long as Isaac keeps moving. Additionally, Gluttony will signal this attack by shivering for a short time before firing, making it easily avoidable. In general, do not spend too long directly horizontally or vertically of Gluttony, and only dash in to deal damage. Remember that as with Vis or Bloodshot Eye, the blood beam will go right through Rocks and other obstacles. Also keep in mind that while he does normal damage with his ranged attacks, he deals a full heart of contact damage. If Isaac follow those steps, your main weakness is patience.
- If Gluttony is frozen while using his blood beam, the attack will stay on screen and continue to hurt Isaac until it is unfrozen.
- The blood beam is able to damage other monsters. This can be utilized in The Chest to quickly dispatch multiple Sins at once.
- Gluttony, like Vis, is a reference to the Vis Sisters from Gish, one of Edmund McMillen's earlier games.
- He may also be a reference to Govenor Cassus Vicus, a boss in the game Clive Barker's Jericho who also has a huge stomach with a vertical fissure along his body that he opens up to spew out blood as attack.
- Edmund McMillen has specifically stated on Formspring that Gluttony is not a reference to the identically-named character Gluttony (who also shoots far-reaching beams from his stomach), from the anime/manga Fullmetal Alchemist.
- Gluttony use to change his expression while attacking from the original game. He no longer does so in Rebirth.