Cognomen Клайс (Claeys 
, Kleis , Клайс 
) , throughout the world, is a common surname. The surname Клайс is habitual in Belgium, where it is quite a common surname, Denmark, where it is quite a rare surname, and Luxembourg. Measured by absolute frequency, this name is the most popular in Belgium, the United States, and France. Much less frequently, Клайс is the forename as well as the last name.