Cognomen Kostyakhin (Kostyakhin 
, Костяхин 
) , all around the world, is a very rare family name. The surname Kostyakhin is habitual in Russia, where it is a very rare surname, Kyrgyzstan, and Kazakhstan.
| VARIANT | COUNTRY |
|---|---|
| Kostyakhin | Russia |
| Костяхин | Kazakhstan, Russia, Kyrgyzstan, Ukraine |