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 | Germany, United Kingdom, Australia, Poland, Denmark |
| Клейн | Azerbaijan, Kazakhstan, Russia, Moldova, Ukraine |
| barys klejn historian, BY (b. 1928) |
|