Claes is a masculine given name, a version of Nicholas, as well as a patronymic surname. It is also spelled Klas, Clas and Klaes.
Claes is a common first name in Sweden. It was also a common name in the Low countries until the 18th century, after which the spelling Klaas was largely adopted. People with the given name Claes include:
Claes is the 7th most common surname in Belgium (16,840 people in 1998) and the most common surname in Belgian Limburg. In contrast, only 405 people have the surname in the Netherlands. People with the last name Claes include: