Surname Casni (Casni 
) , all over the world, is a very rare last name. The last name Casni is habitual in Croatia, where it is a rare surname, Malaysia, where it is a very rare surname, and Italy, where it is an extremely rare surname. Not in comparison with a country's population, it is commonest in Croatia, Malaysia, and Germany. More frequently, Casni is the forename as well as the last name.