Zelos (Ζηλος) is the daimon or God of eager rivalry, emulation, envy, jealousy, and zeal. He is the son of Pallas and Styx. Zelos and his siblings (Nike, Bia, and Kratos) are the winged enforcers of Zeus.
Zelos may have been the same as Agon, the daimon of contest, that was worshiped at the site of the Olympic Games. Zelos is also sometimes identified with Phthonos, the spirit of romantic jealousy. He is also closely connected with Eris, the goddess of discord and strife. His parents are Pallas (the Titan of war craft) and Styx (the goddess of Hate and the River Styx in the Underworld was named after her).