Family name Castillan (Castellano 
, Castillan 
, Castellanus ) , in the entire world, is a common cognomen. The family name Castillan is characteristic of Monaco, where it is quite a common surname, Venezuela, and Argentina (explore the name in all countries). In absolute terms, it is the most numerous in Italy, Argentina, and Venezuela. Much less frequently, Castillan is the forename as well as the last name.