Decalion (Also pronounced as Deukalion) was the son of Prometheus, a son of Iapestos, a descendant of human beings.

His mother is possibly Klymene or another Titaness.

The Deluge

Deucalion and Pyrrha was the only survivor of Zeus's Deluge. He and his wife, Pyrrha, were told to build an ark by Prometheus, a wise Titan and father of Deucalion, asking an Oracle of Themis how to repopulate the earth. They were told to throw rocks behind their shoulders. The rocks thrown by Deucalion became Men, and the rock thrown by Pyrrha became Women, and the Earth was repopulated.

Alternative Ending

Zeus grants Deucalion any wish, and he chooses to repopulate the earth, and Zeus tells him how.