Cognomen ฤทธิ์ฤทัย (ฤทธิ์ฤทัย 
) , in the entire world, is an extremely rare family name. The last name ฤทธิ์ฤทัย is habitual in South-eastern Asia, particularly Thailand, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| ฤทธิ์ฤทัย | Thailand |