Family name Nanthajak (Nanthajak 
) , worldwide, is a very rare surname. The surname Nanthajak is habitual in South-eastern Asia, particularly Thailand, where it is a very rare surname. Much less frequently, Nanthajak is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Nanthajak | Thailand |
Warin, Chalita, Yupaporn, Uthaiwan, and Kanjanaporn