Cognomen Eustach (Eustach 
) , around the globe, is a very rare last name. The last name Eustach is characteristic of Tanzania, where it is a rare surname, China, where it is an extremely rare surname, and Brazil. Likewise, Eustach is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Eustach | Germany, China, Czechia, Tanzania, Slovakia |
Efstathios, Eustac, Eustacchio, Eustace, Eustache, Eustachio, Eustachy, Eustacio, Eustacius, Eustacjusz, Eustahije, Eustaqui, Eustaquio, Eustasio, Eustasius, Eustathios, Eustazio, Eustazy, Eustațiu, Eustácio, Eustáquio, Evstafy, Evstahij, Ostap, Stathis, Ευστάθιος, Στάθης, Астафий, Евстатий, Евстафий, Евстахий, Остап, Остафий, Стафей, Эсташ, Юстас, and Євстафій