Cognomen Illarion (Илларион 
, Иларион 
, Illarion 
) , in the world, is a rare surname. The last name Illarion is characteristic of Moldova, where it is quite a rare surname, Bulgaria, and Armenia, where it is a rare surname. In absolute terms, it is commonest in Bulgaria, Moldova, and Malaysia. More frequently, Illarion is the forename as well as the last name.