Family name Seyong (Seyong 
, 세용 ) , worldwide, is a rare last name. The cognomen Seyong is habitual in South-eastern Asia, particularly Malaysia, where it is a rare surname, Myanmar, where it is a very rare surname, and Philippines. Measured by absolute frequency, it is the most numerous in Philippines, China, and Malaysia. Much more frequently, Seyong is the forename as well as the last name.