In Greek mythology, Hemera was a primordial goddess, born of Erebus. She was the goddess of the daytime.

Hemera's sister, Nyx, was the goddess of the night. Hemera left Tartarus just as Nyx entered it; when Hemera returned, Nyx left.

Thalassa, the primordial sea goddess, was the daughter of Hemera and her brother, Aether.