Hades is the supreme god of the underworld in ancient Greek mythology. It is also the name of the underworld itself.

NPS
Charon (boatman of the Styx)

Megaera (one of the Erinyes/Furies)

Cerberus (gate guardian)

Hypnos (god of sleep, keeper of passages)

Shadow Archivist (an unnamed employee of the Office of the Dead)