Last name Castaña (Castaña 
, Kastano 
) , throughout the world, is a rare surname. The surname Castaña is characteristic of Uruguay, where it is a rare surname, Greece, and Argentina, where it is a very rare surname. Not in comparison with a country's population, the name is most common in Argentina, Spain, and Colombia. Very seldom, Castaña is the forename as well as the last name.