Cognomen 介朗 (Guerin 
, Guérin , 介朗) , in the world, is a common surname. The family name 介朗 is habitual in France, where it is quite a common surname, Monaco, and Ireland. Measured by absolute frequency, it most frequently occurs in France, the United States, and Canada. Very seldom, 介朗 is the forename as well as the last name.