To create an Danish primary patronym, the suffix -sen (= 'son') or -datter (= 'daughter') is added to the father's name.
Sometimes the genitive form of the father's name is used before adding the suffix. You will find the genitive forms of Danish names in the grammar tables on the respective name pages. In Danish, usually just the suffix -s is added directly to the name.
|Name||Son's patronym||Daughter's patronym|
Due to the proximity to Germany, Denmark was influenced by German naming fashions already in the Middle Ages. Denmark was the first Nordic country to abandon the use of primary patronyms. Beginning in the aristocracy, the Danish started to take hereditary surnames modelled on the German pattern, often occupational names like Koch = 'cook', Møller = 'miller' or Schmidt = 'smith' as well as ethnic names like Holst = 'from Holstein' or Friis = 'from Frisia'.
When hereditary surnames became mandatory in 1828, most Danes who had not taken another surname before, decided to "freeze" their primary patronyms so they became secondary, hereditary patronyms instead and could function as a surname. Because of this early change from primary to secondary patronyms, Denmark has today very few names used by quite many citizens.
As many Danes use the same secondary patronyms, it has become common to use additional names (e.g. a farm name) as a middle name.
Many Danes took a farm name instead or additionally to the patronymic name. Also other place names were used, e.g. priests liked to take place names for a surname.
19 of the 20 most common Danish surnames are secondary patronyms.
Source: DST as of 1 January 2022