Binding of Isaac: Rebirth Wiki

Disambig.png This article is about the playable character. For other uses, see ??? (Disambiguation).

???, also known as the Blue Baby, is a character unlocked by defeating Mom's Heart Mom's Heart ten times. He starts with three Soul Heart Soul Hearts, and his health meter is unique in that he cannot gain red heart containers. If an item would grant him a red heart container (including an empty one), it adds a Soul Heart Soul Heart instead.


  • Sleeping on a bed will give ??? three Soul Heart Soul Hearts.
  • Enemies who deal full hearts of damage can be very dangerous in the early floors of the game.
  • The Poop The Poop - While not the most useful item, it can allow ??? to cross small gaps by bombing the Poop Poop from the opposite side, much like one would for Rocks. Furthermore, in rooms with non-flying enemies that chase the player (except Spider Spiders), the poop can be used in a corner of the room making ??? untouchable, allowing the player to kill them without taking damage (if the player moves away from the pile of Poop generated, this will no longer work).
    • Other utilities to the poop includes generating pickup, repelling projectiles once per room and destroying retracted spikes, benefitting ???'s defensive playstyles.
  • Added in Afterbirth † Bone Heart Bone Hearts grant an empty Bone Heart upon pickup, but they cannot be refilled using Red Hearts.
  • Added in Repentance The amount of Soul Heart Soul Hearts it costs to purchase an item in Devil Room Devil Room deals is equal to its Red Heart container cost.
  • Added in Repentance ??? has an innate Added in AfterbirthLil Larva Lil Larva effect; destroying a poop while playing as him will spawn a Blue Fly.

Item Interactions[]


  • Removed in RepentanceAbaddon Abaddon costs three Soul Hearts and grants six Black Hearts, damage up, fear shot, and no negative effects to ???. Abaddon can be bought safely regardless of current health, because its price can be deducted from the acquired Black Hearts retroactively.
    • Added in RepentanceAbaddon Abaddon will give 2 black hearts on pickup, essentially refunding the cost to obtain the item from a Devil Room.
  • Ankh Ankh is effectively a 1up! 1up! for ???.
  • Added in Afterbirth / Removed in RepentanceAthame Athame can be used to produce black hearts upon taking damage.
  • Balls of Steel pills or V - The Hierophant V - The Hierophant grant two soul hearts, both of which are more useful than normal HP up items.
  • The Rune of Dagaz Rune of Dagaz grants one soul heart as well as lifting any curses.
  • Removed in Afterbirth The XI - Strength XI - Strength card gives ??? a permanent soul heart.
  • Book of Revelations Book of Revelations Spawns soul hearts.
  • Ceremonial Robes Ceremonial Robes costs Removed in Repentance three Added in Repentance two Soul Hearts and grants three Black Hearts and damage up. Like Abaddon Abaddon, this item is always safe to take.
  • Added in AfterbirthCrown of Light Crown of Light will always activate when entering a room, but still deactivates after taking damage.
  • Mitre Mitre and Daemon's Tail Daemon's Tail replace useless Red Hearts with Soul and Black Hearts respectively.
  • Dark Bum Dark Bum converts useless Red Hearts into Black Hearts and Spiders.
  • Dead Cat Dead Cat will set Soul Hearts to 1, but can be used to gain devil deals by sacrificing the extra lives.
  • Added in Afterbirth †Dim Bulb Dim Bulb is able to be activated every room due to the single charge on The Poop The Poop, providing a consistent stat boost.
  • Gimpy Gimpy has a chance to spawn Soul Hearts when hit.
  • Added in Afterbirth †Hallowed Ground Hallowed Ground turns all The Poop The Poop uses into holy poops.
  • Lazarus' Rags Lazarus' Rags causes ??? to be resurrected as Lazarus Risen Lazarus Risen when he dies, allowing the gathering of heart containers. Once this happens, however, you are no longer playing as ???, and therefore cannot get any of his achievements/unlocks. The same effect happens with the use of Judas' Shadow Judas' Shadow.
  • Added in Afterbirth / Removed in RepentanceMaw of the Void Maw of the Void can produce Black Hearts.
  • Midas' Touch Midas' Touch makes The Poop The Poop create Golden Poop Golden Poop.
  • Monkey Paw Monkey Paw will drop 3 Black Hearts, but must take damage for each one to spawn.
  • Petrified Poop Petrified Poop is useful early on to get more pickups from The Poop The Poop every room.
  • The Polaroid The Polaroid and The Negative The Negative will always activate when taking damage.
  • The Relic The Relic, which is generally useful, is especially useful to ??? as it spawns Soul Hearts.
  • Satanic Bible Satanic Bible generates Black Hearts.
    • Added in Repentance Using Satanic Bible now also causes boss items to turn into devil deals that cost hearts, so it may be best to hold off on using it until after the boss fight.
  • Added in AfterbirthSerpent's Kiss Serpent's Kiss can produce Black Hearts by poisoning enemies.
    • Added in Repentance Serpent's Kiss now only produces Black Hearts from contact damage poison, making it slightly less useful for ???.
  • Squeezy Squeezy and Added in AfterbirthMr. Dolly Mr. Dolly increase ???'s tears and can grant Soul Hearts.
  • Whore of Babylon Whore of Babylon is always active.
  • Added in RepentanceBirthright Birthright will double the effectiveness of HP upgrades, meaning ??? gains twice as many soul hearts as normal.
    • This can be exploited with Converter Converter to generate unlimited HP.
  • Added in RepentanceFortune Cookie Fortune Cookie can give a soul heart upon use.


  • Items that directly add Red Hearts to the health bar, such as Yum Heart Yum Heart, Added in RepentanceYuck Heart Yuck Heart or full health pills, are useless. However Eternal Heart Eternal Hearts still act as an extra half a heart and become a full soul heart at the end of the floor making Prayer Card Prayer Card viable.
  • Blood Donation Machine.png Blood Donation Machines and Devil Beggar.png Devil Beggars are riskier, as they deplete health that is harder to replenish.
  • Removed in Repentance Cursed Skull Cursed Skull will automatically teleport ??? out of the room upon taking any damage, as he doesn't have any Red Hearts. This can be used to easily warp out of the Boss Rush Boss Rush room, but is mostly an annoyance.
    • Added in Repentance Works only at half a soul heart.
  • Added in Afterbirth / Removed in RepentanceGlass Cannon Glass Cannon will bring ??? down to half a Soul Heart, and not give back any health upon leaving a room due to ???'s lack of Red Hearts. This item essentially takes away most of the player's health in exchange for a single high damage tear.
    • Added in Repentance This effect no longer applies in Repentance, making it a more viable choice. Even so, caution should be used, as taking damage will cause all subsequent damage taken in the room to be two full soul hearts, making this especially risky for ???.
  • Guppy's Paw Guppy's Paw, since requiring Red Hearts to convert, would be a useless item to hold (but should still be picked up and swapped back to get credit towards the Guppy transformation). Guppy's Paw may still be used to activate Broken Remote Broken Remote.
  • Removed in Repentance Judas' Tongue Judas' Tongue doesn't lower the price of Soul Heart Devil deals.
  • Little C.H.A.D. Little C.H.A.D. is useless unless paired with Dark Bum Dark Bum or Added in RepentanceApple of Sodom Apple of Sodom, where it becomes very useful.

Unlockable Achievements[]


  •  ??? appears in the original Binding of Isaac.
    •  ???'s unlock requirements in Rebirth are the same in the original Binding of Isaac.
  • The name "Blue Baby" had not appeared in the game itself until the Afterbirth expansion, with a co-op baby named as such.
  •  ???'s common nickname, Blue Baby, is a reference to blue baby syndrome, in which a baby's skin complexion appears blue from a lack of oxygen in its blood due to a congenital heart defect.
  • Many of Edmund's older flash games from Newgrounds feature ??? and Brother Bobby Brother Bobby. ??? was Edmund's mascot from 1996-2002.
  • In several cutscenes, Isaac is depicted suffocating inside a chest. ??? is first seen inside an identical chest, and ??? ??? is the follow up boss after Isaac Isaac. Blue skin tone is typically used to show suffocation, and X eyes imply that the character is either knocked out or deceased.
    • After death, the bowels of the deceased will loosen, causing them to defecate themselves. This is most likely the reason ??? starts with The Poop The Poop.
  • Unlike many of the other characters, ??? does not appear in the Bible or any religious scripture. He is the first character with this distinction, and the only one to appear in the original Binding of Isaac - the second being The Lost The Lost in Rebirth, third being Keeper Keeper in Afterbirth and fourth being The Forgotten The Forgotten in Afterbirth+.
  • The Ankh Ankh will resurrect any character as ???, even before he is unlocked.
  • Although "Blue Baby" is considered an unofficial nickname for ???, the character is referred to by this name in some of the game's code. One example of this is the image file for the character, named character_006_bluebaby.
  •  ???'s look originally came from Dead Baby Dressup, one of Edmund McMillen's first Flash games.
  •  ???'s starting health is listed as "-1" on the character selection screen.
  • As a secret character, ??? does not appear on the character select screen until unlocked.