Kronos

Kronos is the evil Titan lord of time and the main threat in the Percy Jackson and the Olympians series. He is the son of Gaia and Uranus. He is the king of the Titans and is father to the Olympian gods. Kronos is the father of Zeus, Poseidon and Hades, as well of Hestia, Demeter, Chiron and Hera. It should be noted that his early life is much like Zeus', who like him was the youngest and most powerful of his siblings, and was asked to defeat his father by his mother. Kronos took over Luke Castellian's body and he was sent back to Tantalus when Luke regained control of his body and defeated Kronos by stabbing himself with a knife.