Surname Sebastyen (Себастиен 
, Sebastyen 
) , worldwide, is a very rare family name. The surname Sebastyen is characteristic of Romania, where it is a rare surname, Canada, where it is an extremely rare surname, and the United States. Not in comparison with a country's population, it is commonest in Romania, the United States, and Russia. Likewise, Sebastyen is the forename as well as the last name.