Last name เสริมสิทธิ์ (เสริมสิทธิ์ 
, Supphasit ) , around the world, is an extremely rare cognomen. The cognomen เสริมสิทธิ์ is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname. Much more frequently, เสริมสิทธิ์ is the forename as well as the last name.