The Missing Poster is a trinket.
- If Isaac dies in a Sacrifice Room while holding it, a particular puzzle piece will be displayed as cause of his death on his last will.
- Dying in a Sacrifice Room while holding it will outright unlock The Lost, regardless of current character.
- If Isaac dies while holding this trinket and has already unlocked The Lost, he will be revived as The Lost and Missing Poster will be consumed.
- If The Lost dies while holding this trinket, he will be revived in the previous room and Missing Poster will be consumed.
- The Lost will not be unlocked if the player is in a Victory Lap or RERUN.
- None of the effects will occur during any Challenges.
- Even if Holy MantleAutomatically negates first taken damage in every room. has been unlocked as one of The Lost's starting items, if any character dies while holding the Missing Poster, The Lost will not hold the Holy Mantle upon revival.
- If Gulp!, SmelterConsumes Isaac's currently held trinket and applies its effect permanently., or MarblesSpawns 3 random trinkets. Taking damage has a small chance to swallow Isaac's currently held trinket, gaining its effect permanently. were used to absorb the poster, its effects will apply and can be used to unlock The Lost and respawn (but the effect still only applies once).
- The puzzle piece will belong to one of four jigsaw puzzles. To which one is indicated by a tiny grey symbol to the top left of the piece.
- The symbol can either be a pixel, a 2x2px square, a 3x3 px square, or four pixels arranged like a plus-sign.
- Each jigsaw puzzle displays an altered last will for the characters Isaac, Maggy, Judas, or Azazel respectively.
- The first scene in Ending 15 shows The Missing Poster pinned to a utility pole, with a silhouette of Isaac's mother who seems to be searching for Isaac in the background.
- There are many puzzle pieces in total. Assembling all of the jigsaw puzzles and figuring out what they meant was initially designed to be collaborative effort of the community.
The Missing Poster in Ending 15.
- 1up!Gives an extra life. Upon death, you will respawn in the previous room with full health and lose the 1up!.
- AnkhUpon death, the player will respawn as ??? with 3 soul hearts.
- Dead CatSets the amount of red heart containers to 1, but gives Isaac 9 extra lives. After dying, Isaac is teleported to the last safe room. New heart containers can be obtained after picking up this item, but after each death, the number of heart containers is set to 1 again.
- Guppy's CollarGrants Isaac a permanent 50% chance to respawn with 1/2 of a red heart after death.
- Judas' ShadowAdds an extra life; upon death, it respawns Isaac as Black Judas with only two black hearts.
- Lazarus' RagsUpon dying, resurrect as Revived Lazarus with one heart container and Anemic item.
- Broken AnkhWhen held, Isaac has a chance to be revived as ???. Can occur multiple times in the same run.
- Missing PosterIf Isaac dies in a Sacrifice Room, a puzzle piece will appear on his last will ( and unlocks The Lost). Revives Isaac as The Lost if unlocked. The Missing Poster then disappears.