???#4

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 ten times. He starts with three 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 instead. While he has no passive starting items, he does spawn in with The Poop.

• Dead Baby - Defeat Mom's Heart on Hard mode as ???.
• Forget Me Now - Defeat Satan as ???.
• The D6 - Defeat Isaac as ???.
• ???'s Soul - Defeat The Lamb as ???.
• Fate - Defeat ??? as ???.
• Cracked Dice - Defeat Ultra Greed as ???.
• Meconium - Defeat Ultra Greedier as ???.
• Fate's Reward - Defeat Hush as ???.
• Blue Baby - Defeat Mega Satan as ???.
• King Baby - Defeat Delirium as ???.
• Eternal D6 - Defeat Mother as ???.
• Montezuma's Revenge - Defeat The Beast as ???.
• The Soiled - Use Red Key (etc.) to open the hidden closet in Home as ???.
• Hive Baby - Earn all Hard mode Completion Marks as ???.

• ??? 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.
• Before Afterbirth, in the original Binding of Isaac, his true name would appear in Isaac's Last Will in parentheses. This detail was overlooked/removed in Rebirth.
• ???'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. ??? 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. 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.
• 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 in Rebirth, third being Keeper in Afterbirth and fourth being The Forgotten in Afterbirth+.
• The 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 "-I" on the character selection screen.
• As a secret character, ??? does not appear on the character select screen until unlocked.
• He shares this trait with The Lost, Keeper, and The Forgotten.
• ??? is likely the manifestation of Isaac's shame, as seen in the final ending of the game. As the narrator says "His shame, his worry, pulled from his being," ??? and The Lost can be seen falling away from Isaac. This makes sense lore- and gameplay-wise, as ??? is Isaac's corpse, and this ending also later shows Isaac's regret about dying as his mother finds his body, and ??? starts with The Poop, and, according to Sigmund Freud, feces represent shame.