Cognomen สมเพ็ชร (Somphet 
, สมเพ็ชร , Sompetch 
) , in the entire world, is quite a rare surname. The family name สมเพ็ชร is habitual in South-eastern Asia, particularly Laos, where it is quite a common surname, Thailand, where it is quite a rare surname, and Cambodia, where it is a very rare surname. Not in comparison with a country's population, it most frequently occurs in Thailand, Laos, and India. Also, สมเพ็ชร is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Somphet | Germany, Thailand, France, Laos, United States |
| สมเพ็ชร | Thailand |
| Sompetch | Thailand, Peru |
| Sompet | India, Thailand, United States, Malaysia |