Worldwide, Klejn (Klejn 
, Клейн 
) is an extremely rare unknown gender given name. More prevalently, Klejn is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| Klejn | Poland, Australia, United Kingdom, Denmark, Germany |
| Клейн | Moldova, Kazakhstan, Azerbaijan, Russia, Ukraine |
| barys klejn historian, BY (b. 1928) |
|