Last name Watchai (วัชชัย 
, Watchai , วัตน์ชัย ) , across the world, is a very rare surname. The cognomen Watchai is habitual in South-eastern Asia, particularly Thailand, where it is a very rare surname. More prevalently, Watchai is the forename as well as the last name.
Srihawong, Weeradetsontonchai, Mongkolsrisawad, Weeradetsuntonchai, Weeradetsunthornchai, Weeradetsonthornchai, Nawapornchaimongkol, Jittirattavoon, Phansaraphum, Kaewpaluk, Chaitawat, Setthasuk, Mahaphaisan, Phothong, Ruerueang, Khotprom, Watcharintarachai, and Kanchanasirirat