Onix may refer to:
ONIX (publishing protocol), XML metadata formats for book publishers Onix (Pokémon), a fictional species in the Pokémon franchise Chevrolet Onix, a subcompact car Onix, a synonym of the legume genus Astragalus
People Onix Cortés (born 1988), judoka from Cuba Onix Concepción (born 1957), Puerto Rican Major League Baseball shortstop
See also Onyx (disambiguation) P-800 Oniks, a Russian/Soviet supersonic anti-ship cruise missile