Cognomen Seyun (Seyun 
) , all over the world, is a rare family name. The family name Seyun is habitual in South Korea, where it is a rare surname, Malaysia, where it is a very rare surname, and Nigeria, where it is an extremely rare surname. In absolute terms, it most frequently occurs in South Korea, China, and Nigeria. More prevalently, Seyun is the forename as well as the last name.