Last name กุลศักดิ์ (กุลศักดิ์ 
, Kunsak 
, Kulsak ) , all over the world, is a rare surname. The last name กุลศักดิ์ is habitual in Thailand, where it is a rare surname, and the United States, where it is an extremely rare surname. Likewise, กุลศักดิ์ is the forename as well as the last name.