Cronus was the Titan who fathered the Olympian gods before Zeus overthrew him.
Cronus was the youngest of the twelve Titans and the son of Uranus and Gaia. He overthrew Uranus after Gaia encouraged him to challenge his father. Cronus then became ruler of the cosmos, but a prophecy warned that one of his own children would eventually defeat him.
To prevent the prophecy, Cronus swallowed each child born to Rhea: Hestia, Demeter, Hera, Hades, and Poseidon. Rhea saved Zeus by hiding him in Crete and giving Cronus a stone wrapped in swaddling clothes instead. Zeus later forced Cronus to disgorge the swallowed children.
The resulting Titanomachy ended with Zeus and his siblings victorious. Cronus is often confused with Chronos, a personification of time from later Greek tradition; the two names became associated in later interpretations but were originally distinct.