|Last appearance||Hercules The Animated Series|
|Occupation||Assistant of Hades|
Ceto is a giant sea serpent who lives in the River Styx which is located in the Underworld. In the film, Hercules fought this monster during the Zero to Hero segment wherein Hercules and Phil where searching for it in an ominous sea, when they finally find Ceto Hercules quickly defeats it and turns it into a fishing trophy. Ceto also appears in the animated series as a resident of the Underworld who attacks anyone who falls into the River Styx.
Ceto was a primordial sea goddess in Greek mythology.
In the film and the episode "Hercules and the Parents Weekend", Ceto is shown as having the tip of its tail forked while in other appearances it is not.