Binding of Isaac: Rebirth Wiki

Disambig.png This article is about the boss. For the posthumous version, see Monstro II. For the enemy, see Ministro. For the item, see Lil Monstro.

Monstro is a boss that can appear in the Basement Basement and the Added in Afterbirth Burning Basement Burning Basement.


  • Hops towards Isaac.
  • Coughs up a large number of disorganized projectiles towards Isaac.
  • Jumps off-screen, aiming to land on top of Isaac. Create a burst of disorganized projectiles in all directions on landing.

Champion Versions Needs to be unlocked[]

Grey: 15% larger and has 25% more HP (312.5). Uses projectile volleys much more often and is unable to jump off-screen.
Red: Two 20% smaller Monstros, each with 55% less HP than the original one (112.5), replace the normal Monstro.



Note: Layouts 1 and 11 are identical. Added in Repentance Layouts 8 and 9 no longer appear, as small boss rooms have been disabled.


  • In the boss room, Monstro can be paired with Fly Flies, Attack Fly Attack Flies, Gaper Gapers, Hopper Hoppers, Frowning Gaper Frowning Gapers, Mulligan Mulligans, Added in Afterbirth Cyclopia Cyclopias, or Added in Afterbirth † Ministro Ministros.
  • When Monstro jumps off-screen, he is cured of all status effects.
  • Removed in Repentance Monstro can't hop over Obstacles.
    • If Isaac is somewhere that Monstro cannot reach, Monstro will jump in place.
    • If Isaac has flight and is over an obstacle, Monstro will essentially be unable to perform any attacks.
      • While Monstro can hit Isaac with his tear barrage because of its tear height, it is very unlikely.
  • Added in Afterbirth † Monstro can rarely spawn in a room with two Blood Donation Machines.
  • Added in Repentance Monstro will spawn in ??? ??? if IV - The Emperor? IV - The Emperor? is used. Defeating Monstro this way will count as defeating Added in Afterbirth Hush Hush for completion mark purposes.


  • Monstro appeared in the original The Binding of Isaac.
  • He is the boss version of the Added in Afterbirth † Ministros.
  • Monstro appears to be missing a tooth which happens to be an item.
  • Monstro is Monster in Portuguese.
  • Added in Repentance Monstro has a new fallback animation.