|Floors of Appearance|| Basement|
|Deals Contact Damage||Yes|
|Type of Tears||"V" Pattern|
The Fat Fly is an enemy in The Binding of Isaac: Rebirth that is encountered on The Basement, The Cellar, The Caves, The Catacombs, The Depths, and the Necropolis floors. It is a large fly that has the body shape of a wasp with an orifice at the end of its body.
- The Fat Fly slowly flies around the room. When it is in range of the player, it will fire two spread tears in a "V" pattern at the player. Fat Flies can sometimes be time consuming to kill, for they can fly over rocks and remain stationary for a moment, not allowing the player to shoot them. Fat Flies can fly over Rocks, Spikes, Holes, and other obstacles.
- If the player does not move, they will avoid all shots by Fat Flies, for Fat Flies shoot in a "V" pattern.