Last name Киллен (Killen 
, Киллен 
) , in all the world, is quite a common surname. The surname Киллен is habitual in Ireland, where it is quite a rare surname, Australia, and Liberia. Not in comparison with a country's population, it is the most numerous in the United States, the United Kingdom, and Australia. Much less frequently, Киллен is the forename as well as the last name.