In Greek mythology, Atlas is a Titan and the brother of Prometheus. After their defeat in the titanomachy, Atlas was forced to hold up the celestial heavens or sky for eternity. He was a skilled astronomer, credited with inventing the first celestial sphere.

'Atlas and the Hesperides' - John Singer Sargent, 1925.
Atlas also features in the myth of Heracles. During his Twelve labours, Heracles visited the garden of Hera, which was tended by the Hesperides (Atlas's daughters) to find the golden apples. Heracles held up the sky while Atlas fetched the apples. Atlas had hoped to trick Heracles to keep holding it but he was outsmarted. In some versions of the myth Heracles built two pillars to hold up the sky, thus liberating Atlas from his burden.

Lucas Cranach the Elder

The Farnese Atlas