Bertelsen and Berthelsen are Danish-Norwegian patronymic surnames meaning "son of Bertel" or cognate "Berthel" (both equivalent of the Biblical Βαρθολομαίος/Bartholomaios, cf. English Bartholomew). There are several people with this surname:
Bertelsen Aage and Gerda Bertelsen, Danish resistance members Aage Bertelsen (1873–1945), Danish painter Albert Bertelsen (1921–2019), Danish autodidact painter and graphic artist Barbara Bertelsen, Danish jurist Brian Bertelsen (born 1963), Danish footballer Carl Bertelsen (1937–2019), Danish footballer Erik Bertelsen (1912–1993), Danish ichthyologist Frederik Bertelsen (born 1974), Danish cyclist Jens Jørn Bertelsen (born 1952), Danish footballer Jes Bertelsen (born 1946), Danish philosopher Jim Bertelsen (1950–2021), American football player Karen Bertelsen, Canadian broadcaster Lise Bertelsen (born 1975), Danish politician Mads Bertelsen (born 1994), Danish footballer Mikael Bertelsen (born 1967), Danish radio and TV personality Niels Bertelsen (1926–1989), Danish boxer Nils Bertelsen (1879–1958), Norwegian sailor Ola Bertelsen (1864–1946), Norwegian jurist and politician Ole Peder Bertelsen (1930–2018), Danish-born oil trader and entrepreneur Rasmus Bertelsen (born 1983), Danish association football manager Trond Erik Bertelsen (born 1984), Norwegian footballeer Verner Bertelsen (1918–2015), American politician William R. Bertelsen (1920–2009), American inventor
Berthelsen Anders W. Berthelsen (born 1969), Danish actor Anne Valentina Berthelsen (born 1994), Danish politician Asii Berthelsen (born 2004), Danish footballer Berit Berthelsen (1944–2022), Norwegian sprinter and long jumper Bernhard Berthelsen (1897–1964), Norwegian politician Hermann Berthelsen, Greenlandic politician Jacob Berthelsen (born 1986), Danish footballer Jens Berthelsen (1890–1961), Danish fencer Jens Peter Berthelsen (1854–1934), Danish fencer Johann Berthelsen (1883–1972), American painter Julie Berthelsen (born 1979), Danish-Greenlandic musician Kiehn Berthelsen (born 1925), Danish speedway rider Kurt Berthelsen (born 1943), Danish footballer Linnea Berthelsen, Danish actress Malik Berthelsen, Greenlandic politician Olga P. Berthelsen, Greenlandic politician Per Berthelsen (born 1950), Greenlandic politician Rasmus Berthelsen (1827–1901), Greenlandic poet and artist Richard Berthelsen (born 1944), American lawyer and labor leader Roar Berthelsen (1934–1990), Norwegian long jumper Villum Berthelsen (born 2006), Danish footballer