In the judgement scene of spell 125, beside the balance, there is an animal. She has the head of a crocodile, the forequarters and mane of a lion, and the hindquarters of a hippopotamus, and she is usually drawn small — considerably smaller than the gods around her, sitting or crouching, sometimes on a plinth, sometimes with her jaws slightly open, watching the scales.
Her name is Ammit, "the devourer", and longer forms give "devourer of the dead" or "swallower of millions" and "great of death". She is not a goddess. She has no cult, no temple, no offerings, no priesthood and no myth. She is an instrument of the tribunal, present for one purpose, and the record of her is almost entirely visual — she is a figure in a picture that accompanies a text.
What she is made of
The three animals are the three most dangerous in the Egyptian environment, the same trio assembled protectively in Taweret. Here the assembly runs the other way: rather than recruiting the threats, the composition concentrates them. Egyptian visual grammar builds a being out of parts that state its capacities, and Ammit's parts all state one thing — the ability to seize and consume something large.
There is a strong argument that the composition is deliberately anti-Taweret, the same components in the same court where Egyptian moral reckoning happened, rearranged from guardian into executioner. Neither figure is a species; both are arguments.
The second death
What she does is where the theology gets interesting, and where the standard Western frame fails.
If the heart fails to balance against the feather of Ma'at, Ammit eats it. The consequence is not torment, imprisonment or punishment of any duration. It is cessation. The person stops. There is no further existence to suffer in, no soul remaining to be tormented, no place to be sent. Egyptian texts call this the second death — the first being ordinary bodily death, which was survivable, and the second being annihilation, which was not.
Egyptian religion, on this point, offers no hell. It offers continued existence in the Field of Reeds or it offers the end of you, and Egyptians found the second prospect terrifying in a way that is worth taking seriously. The entire apparatus of Egyptian funerary practice — the preserved body, the tomb, the name carved and repeated, the offerings, the statue that could receive the ka, the shabtis, the spells — is directed at maintaining the conditions for continued existence. Erasing a name from a monument was a real and severe punishment because it attacked that continuity. Against that background, an animal that eats the heart and leaves nothing is the worst outcome the culture could imagine.
The frightening part is the heart
There is a spell for this, numbered 30B, cut into the flat base of the heart scarabs laid on a mummy's chest, and its addressee is the dead person's own heart. Do not oppose me, it says; do not act as a witness; make no case to the one who holds the scales; say nothing false about me.
That request tells you exactly what an Egyptian expected to happen. The danger at the tribunal is not a prosecuting deity or a hostile judge; Anubis is merely checking the plumb line, Thoth is merely writing. The danger is that your own heart — the organ Egyptians held to be the seat of a person's character and recollection, and the only one left inside the corpse when the embalmers finished — will testify honestly.
So the amulet is an attempt to suborn a witness, buried on the chest of the accused. Egyptian religion contains, at the same moment, a demanding ethical standard and a piece of equipment for defeating it, and it never resolved the tension in either direction.
Where she actually appears
Her best-known depiction is in the Papyrus of Ani in the British Museum, a Nineteenth Dynasty Book of the Dead of exceptional quality, where she sits attentively beside the scales while the ceremony proceeds. She appears in comparable judgement vignettes in many other papyri, on coffins, and on tomb walls with the same scene.
Occasionally she is shown by a lake of fire, or in association with it, in versions where the destruction has a location as well as an agent. She also appears in some underworld book scenes among the beings who dispose of enemies.
What she does not do is anything else. She never speaks, never travels, never appears outside the judgement context and is never invoked, petitioned or feared in the way a god might be. There is no evidence anyone ever addressed her.
In the modern imagination
She has had an unexpected surge in visibility, largely through Moon Knight, which made her a speaking antagonist with a plan — imprisoned by the other gods, released, intending to judge people before they had committed their crimes. All of that is invention. The show's version is a goddess with agency and a philosophy; the Egyptian figure is closer to a piece of court equipment.
Games have generally used her as a boss monster, which at least keeps the composite form. The recurring modern instinct is to promote her to a villain, and it runs into the same problem that dogs Set and Anubis in popular treatment: it imports a moral drama with an antagonist into a system that was organised around procedure and measurement.
Questions about the devourer
Was she ever shown eating a heart?
Very rarely, and this is one of the more striking things about the iconography. The scene almost always depicts the moment before — the balance in equilibrium, the outcome pending, Ammit waiting. A Book of the Dead was made for a specific named person, and it was in their interest for the picture to show a favourable or at least an undecided outcome. The papyri are, among other things, optimistic documents, and depicting the failure would have been depicting the owner's failure.
Does she count as a demon?
The word carries assumptions that do not transfer. Egyptian has categories for beings that are not gods and not people — guardians of gates, knife-wielding figures in the underworld books, messengers of Sekhmet — and these are generally functionaries operating within the divine order rather than rebels against it. Ammit belongs in that category: she is authorised, she works for the tribunal, and she has no independent will. Egyptian religion has almost nothing that maps onto a demon in the later Western sense, and its only genuinely external enemy is Apep.
If everyone had the spell, did anyone ever fail?
The texts never describe an individual failing, which is unsurprising given that every surviving copy was commissioned by someone hoping to pass. Whether Egyptians thought failure was common, rare or largely hypothetical is not recoverable. What the corpus does show is anxiety — a great many spells exist for not dying a second time, not having the heart taken away, not being destroyed — and people do not accumulate protections against outcomes they consider impossible. The Duat page follows that anxiety through the rest of the night journey.