Ammit the Devourer

Ammit the Devourer is a demon that lives in the Hall of Judgment. He eats your heart when you die if your heart does not equal the Feather of Truth in weight, indicating a wicked life.

Background
Ammit the Devourer sits at the Scales of Justice in the Hall of Judgment. The dead have their hearts weighed against the Feather of Truth; if the heart weighs more than the Feather, the deceased is deemed to be wicked. The wicked heart is then thrown to Ammit, who eats the heart, banishing the soul for all of eternity. After Osiris was imprisoned, the Hall of Judgment fell into disrepair while Anubis was powerless to stop it. With nothing to eat, Ammit fell into a deep slumber.

The Red Pyramid
Ammit is sleeping when Carter, Sadie, and Khufu are led to the Hall of Judgment by Anubis. He whimpers in his sleep when he hears his name, making Sadie wonder if he was dreaming of chasing rabbits. When Osiris returns to the Hall of Judgment, Ammit returns to his duty of devouring hearts.

Appearance
Ammit has the head of a crocodile, the body of a lion, and the backside of a hippopotamus. He is the size of a poodle, and Thoth describes him as "an adorable little thing". Carter assumed that he would be bigger.

In Mythology
The myths describe Ammit as female. In the series Ammit is described as small, yet depications of the soul eater in art and on tombs show a large man-sized creature. He was said to travel to earth with blackened wings, and decapitate all whom didn't obey Anubis's orders of sacrifice.