Cognomen Fthenos (Fthenos 
) , worldwide, is a rare family name. The family name Fthenos is habitual in Greece, where it is quite a rare surname, Canada, where it is a very rare surname, and Germany, where it is an extremely rare surname. Not in comparison with a country's population, the name is most common in Greece, Canada, and the United States.
| VARIANT | COUNTRY |
|---|---|
| Fthenos | Germany, Greece, United States, Canada |