Family name Penroaj (Penroaj 
) , all around the world, is a very rare cognomen. The family name Penroaj is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname.
| VARIANT | COUNTRY |
|---|---|
| Penroaj | Thailand |
Smattachai, Puthipong, Theeradech, Teeraphan, Patanapong, and Theeraporn