Family name เพ็ญรัตน์ (เพ็ญรัตน์ 
, Penrat 
, Phenrat ) , all around the world, is quite a rare surname. The family name เพ็ญรัตน์ is characteristic of Thailand, where it is quite a rare surname, France, where it is a very rare surname, and the United States, where it is an extremely rare surname. Likewise, เพ็ญรัตน์ is the forename as well as the last name.