Iapetus was the father of Atlas in Greek mythology.
Atlas was one of the Titans and was commonly described as the son of Iapetus and the Oceanid Clymene, though some traditions give different maternal names. His brothers included Prometheus, Epimetheus, and Menoetius.
During the golden-apples episode, Hercules encountered Atlas and arranged for him to retrieve the apples from the garden of the Hesperides. Hercules temporarily took Atlas’s burden of holding up the sky, then tricked him into resuming it after the apples were obtained.
This family detail can be confused with Cronus, who was Atlas’s grandfather in the usual genealogy. Cronus was the father of Iapetus, while Iapetus was Atlas’s father. The question concerns Atlas’s mythological parentage, not Hercules’ own ancestry.