Family name Лассен (Lassen 
, Лассен 
) , in all the world, is a common last name. The surname Лассен is habitual in Denmark, where it is quite a common surname, Norway, where it is quite a rare surname, and Namibia. In absolute terms, it is commonest in Denmark, Germany, and the United States. Very seldom, Лассен is the forename as well as the last name.