Last name โออิน (Oin 
, Oain 
, โออิน ) , all around the world, is quite a rare surname. The cognomen โออิน is characteristic of Thailand, where it is a rare surname, Malaysia, and Taiwan. Measured by absolute frequency, it most frequently occurs in South-eastern Asia, particularly Thailand, Indonesia, and Malaysia. Much less frequently, โออิน is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Oin | Indonesia, Taiwan, Romania, Malaysia, Thailand |
| Oain | India, United States, Brazil |
| โออิน | Thailand |