Clausen [ˈklauˀsən] is a Danish patronymic surname, literally meaning child of Claus, Claus being a German form of the Greek Νικόλαος, Nikolaos, (cf. Nicholas), used in Denmark at least since the 16th century. The spelling variant Klausen has identical pronunciation (as does the often interchangeable Claussen). The two variants are number 34 and 85 on the top100 of surnames in Denmark. Occurrences of Clausen/Klausen as a surname outside Denmark and Schleswig-Holstein are due to immigration. Immigrants to English-speaking countries sometimes changed the spelling to Clauson.
Clausen is a quarter in central Luxembourg City, in southern Luxembourg.
In 2011, the quarter had a population of 798 people.
Its parish church, St. Cunegonde, is the location for Luxembourg's weekly celebration of Tridentine Mass on Sundays at 11.30 a.m. as of 5 October 2014.
The church has a number of notable wall paintings depicting the life of St. Cunegonde.
The statesman Robert Schuman was born in a house which his parents were renting at the time along the rue Jules Wilhelm in Clausen. He later attended the local primary school. In 1985 the house was purchased by the state and it is now home to a small research institute. The baptismal font used for his baptism into the Catholic church may be found in the local parish church of St. Cunegonde where an image in his boyhood likeness may also be found on a large wall painting to the left of the altar depicting an event in the life of St. Cunegonde. The artist used local people as models for a crowd scene and the young Robert Schuman was used to represent a small boy.