Family name Kostyanets (Kostyanets 
, Костянец 
) , around the globe, is a very rare cognomen. The last name Kostyanets is habitual in Belarus, where it is a rare surname, Russia, where it is a very rare surname, and Kazakhstan.
| VARIANT | COUNTRY |
|---|---|
| Kostyanets | Russia, Ukraine |
| Костянец | Kazakhstan, Russia, Ukraine, Belarus |
Костианетс, Костянетс, and Костянець