In the entire world, Риу (Riou 
, Rioux , Риу 
) is a rare mostly masculine, but infrequently girly forename. The first name Риу is habitual in Greece, where it is a rare masculine name, Algeria, and France, where it is a very rare dominantly boy's, but infrequently girly name. Measured by absolute frequency, it is the most numerous in Indonesia, Algeria, and France. Much more frequently, Риу is the last name as well as the forename.