Tityos was the son of Zeus and the mortal princess Elara. To conceal the pregnancy from his wife Hera, Zeus hid Elara deep beneath the earth, so that Gaia, the Earth, is sometimes named as Tityos's gestational mother — a tradition that accounts for his giant size.

He was the father of Europa, who lay with Poseidon and bore Euphemus, one of the Argonauts.

Tityos attempted to rape the goddess Leto, in several accounts at the instigation of Hera. He was struck down by Leto's protective children, the twin deities Apollo and Artemis; in some versions he was instead slain by the thunderbolt of his father, Zeus.

Homer's Odyssey describes the location of the attack with references to the region of Pytho (Delphi) and Panopeus in Phocis. Ancient writers who recount or allude to his story include Homer, Pindar, Pausanias, Lucretius, and several Roman poets such as Virgil, Horace, Ovid, and Seneca.

As punishment for his assault on Leto, Tityos was condemned to eternal torment in the Underworld. He was stretched out and held fast while two vultures fed continually on his liver, which grew back every night so that the torture could never end.

In Homer's Odyssey he is seen sprawled on the ground, his vast body covering nine acres. His punishment is frequently compared to that of Prometheus, whose liver was likewise devoured by a bird and renewed; he is grouped among the great sinners of Tartarus alongside Tantalus and Sisyphus.

Local traditions in Phocis preserved a hero-cult of Tityos that appears to predate the Olympian gods. The geographer Strabo recorded that the inhabitants of Panopeus showed visitors a cave called Elarion, named after Elara, the mother of Tityos, together with a hero-shrine of Tityos himself.

This local reverence suggests an older, pre-Olympian figure whose cult was later subordinated to the worship of the Olympian deities who punished him. A painting by Polygnotus at Delphi, described by Pausanias, also depicted Tityos among the figures of the Underworld.