Cognomen Ruethaikarn (Ruethaikarn 
) , throughout the world, is an extremely rare family name. The cognomen Ruethaikarn is characteristic of South-eastern Asia, particularly Thailand, where it is an extremely rare surname. More frequently, Ruethaikarn is the forename as well as the last name.
Kaito, Phansa, Jansuk, Nitkhamharn, Punpongpipat, Horprasertkij, Watcharamekkhala, and Sukontapatipak