Last name Cửu (Cửu 
) , globally, is a rare family name. The surname Cửu is characteristic of South-eastern Asia, particularly Vietnam, where it is a rare surname. Likewise, Cửu is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Cửu | Vietnam |
| trịnh đình cửu VN (b. 1906) |
|