Ceto (Keto) was a primordial deity of the sea from Greek mythology. She was the daughter of the Titans Pontus and Gaea, and personification of the risks that the sea introduced. Her partner was Phorcys, with whom she had many children. They all were monsters, called Phorcydes. The Phorcydes comprised Echidna, the Gorgons (the 3 sisters Euryale, Stheno and Medusa), the Graeae, and Ladon. Sometimes, the monster Scylla was regarded as a child of Ceto(Keto). These children tend to be constant across sources, though Ladon is sometimes mentioned as a child of Echidna by Typhon and so Phorcys and Ceto’s grandson.
Ceto is also known in several Greek texts like Crataeis, which means “powerful,” and since Trienus, which means “in three years.” Some scholars combined her using the goddess of Hectate, whose nicknames are also Crataeis and Trienus.