Last name Касія (Kassia 
, Касія 
) , across the world, is a rare cognomen. The surname Касія is characteristic of Burkina Faso, where it is a rare surname, the Democratic Republic of the Congo, and Portugal. Measured by absolute frequency, it is commonest in the Democratic Republic of the Congo, Burkina Faso, and Brazil. Much more prevalently, Касія is the forename as well as the last name.