Gaia is the primordial goddess in Greek mythology and personification of the earth. From her sprang all life including the primordial sky god Uranus. From her and Uranus were born the Titans and the Titans gave birth to the Greek gods.
Gaia created this sickle so she could get revenge on Uranus for imprisoning her more monstrous children, the Cyclopes and Hecatonchires, in Tartarus. She gave this sickle to the Titan Cronus. The sickle was used to castrate Uranus. Cronus became the king of the gods until overthrown by his son Zeus.