The Greek god Zeus feared nothing because he was the king of the Olympic pantheon and ruled over gods, men and monsters. Before his rise to supreme power, his mother protected him from his father. When Zeus grew strong enough, he overthrew Cronos and the Titans.
The Titans were the siblings of Zeus' father, Cronos. They were gigantic in form and ruled the heavens under Cronos before Zeus and his siblings were born to the goddess Rhea, Cronos' wife. Fearing a prophecy that his children would dethrone him, Cronos swallowed them all as babies. Rhea helped Zeus escape that fate, and Zeus killed Cronos. Then, Zeus restored his siblings as the new rulers of the world.