Family name Seredyak (Seredyak 
, Середяк 
) , across the world, is a rare cognomen. The surname Seredyak is habitual in Ukraine, where it is a rare surname, Kazakhstan, where it is a very rare surname, and Russia.
| VARIANT | COUNTRY |
|---|---|
| Seredyak | United States, Ukraine |
| Середяк | Russia, Kazakhstan, Ukraine |