Cognomen ฤทธิ์ธรรม (ฤทธิ์ธรรม 
, Rittham ) , across the world, is a very rare last name. The family name ฤทธิ์ธรรม is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname.
| VARIANT | COUNTRY |
|---|---|
| ฤทธิ์ธรรม, Rittham | Thailand |