Cognomen Osao (Osao 
) , all around the world, is a rare family name. The cognomen Osao is habitual in Japan, where it is a rare surname, Philippines, where it is a very rare surname, and Nigeria, where it is an extremely rare surname. Much less frequently, Osao is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Osao | Philippines, Japan, Brazil, United States, Nigeria |