|Floors of Appearance||All Floors|
|Deals Contact Damage||Yes|
|Type of Tears||None|
The Eternal Fly is an enemy in The Binding of Isaac: Rebirth that is encountered on every floor in the game. It is a small white fly.
- The Eternal Fly slowly flies around its host, possible hosts being Holy Leeches, Hangers, Blue Baby (???) (Boss), and Corny Poop. It deals contact damage. Eternal Flies are invincible until their host dies, in which they can then be killed, acting exactly like Attack Flies. Eternal Flies can fly over Rocks, Spikes, Holes, and other Obstacles.
- If the player has Skatole, Eternal Flies still fly around their host and deal contact damage, but, when the host is killed, they turn into Attack Flies that cannot harm the player. It is unknown as to whether Eternal Flies are programmed to die when Holy Leeches die or if the explosion kills them.