Last name เถ้า (Thao 
, Ashrof 
, Ashn 
) , globally, is a common surname. The last name เถ้า is characteristic of Macao, where it is quite a common surname, Vietnam, and Laos. Measured by absolute frequency, it is the most numerous in Vietnam, the United States, and Malaysia. Also, เถ้า is the forename as well as the last name.