Rhea was one of the Titans, daughter of Uranus and Gaea. She was the sister and wife of Cronus, also a Titan. She was responsible for the way things flow in the kingdom of Cronus (her name means 'that which flows').
Rhea and Cronus had six children; Hestia, Hades, Demeter, Poseidon, Hera and Zeus. Cronus, afraid that he would be overthrown by his children just like he had done with his father, decided to swallow all of them. However, he was tricked by Rhea, who managed to save Zeus from his father. When Zeus grew up, he forced his father to disgorge his siblings and eventually overthrew him.
Although Rhea was considered the "mother of gods", similarly to Gaea and Cybele, she did not have a strong cult and many followers. She had a temple in Crete, the place in which she hid Zeus to save from his father. In art, she started appearing in the fourth century BC; however, she was often depicted with characteristics similar to those used for Cybele, thus making the two goddesses indistinguishable. Rhea was often symbolised as a pair of lions that pulled a celestial chariot. This symbol was often placed on city gates, the best known example being that at the city of Mycenae, where two stone lions guarded the gates.