Around the globe, Kosaj (Косай 
, Kosaj 
) is a rare boy's first name. The given name Kosaj is characteristic of Kazakhstan, where it is quite a rare masculine name, and Azerbaijan. Much less frequently, Kosaj is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| Косай | Kazakhstan, Ukraine, Azerbaijan, Russia |
| Kosaj | Malaysia, India |