Surname Sitthichai (สิทธิชัย 
, Sitthichai 
, สิทธิไชย ) , in the world, is quite a rare cognomen. The family name Sitthichai is habitual in Thailand, where it is quite a rare surname, Malaysia, where it is a very rare surname, and the United States, where it is an extremely rare surname. More frequently, Sitthichai is the forename as well as the last name.