Family name สมฤทธิ์ (สมฤทธิ์ 
, Somrit 
, Somsarit 
) , all around the world, is quite a rare last name. The surname สมฤทธิ์ is habitual in South-eastern Asia, particularly Thailand, where it is quite a rare surname, and Malaysia, where it is a very rare surname. Also, สมฤทธิ์ is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| สมฤทธิ์ | Thailand |
| Somrit | Thailand, United Kingdom, United States, India, Malaysia |
| Somsarit | Thailand, Canada |
Smrtti, and Somritrach