Surname Ratchasak (ราชศักดิ์ 
, Ratchasak ) , throughout the world, is a very rare family name. The last name Ratchasak is habitual in South-eastern Asia, particularly Thailand, where it is a rare surname. Much more prevalently, Ratchasak is the forename as well as the last name.
Samam, Kaewmala, Khajontraveechok, Pornchuen, Taweesri, Wongngern, Chauychuwong, Potjanaaree, Plubplung, Rueangsri, Rueangchai, Jantawaree, Tananimit, Wangkwamchop, Kaewwichian, Kulchaiyakul, Thammakumpee, Wiriyaphan, Somyanonthanakul, Chalongkulsak, Suwanchatree, Thanapornsin, Chumsang, Soontorn, Siramput, Sawekvapee, Demoh, Yajit, Susewi, Buabut, Kitima, Phetla, Ranron, Eaimvijarn, Yeuram, Saochun, Buranapanichkit, Sengmee, Arunrot, Chochun, Boripan, Buachey, Petsong, Pornarchaphipat, Ragsuwong, Lekyindee, Junrung, Hanwanchai, Arunroj, and Tassananutriyhakul