Cognomen Kocaj (Kocaj 
, Коцай 
) , in the world, is quite a rare last name. The cognomen Kocaj is habitual in Albania, where it is quite a rare surname, Poland, where it is a rare surname, and Slovakia. Measured by absolute frequency, this name is the most popular in Poland, Albania, and Ukraine. Likewise, Kocaj is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Kocaj | Australia, United States, Greece, Poland, Albania |
| Коцай | Ukraine, Russia, Kyrgyzstan, Kazakhstan |
| željko kocaj BA (b. 1958) |
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| janusz kocaj German actor, DE (b. 1987) |
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