Thomsen is a Danish patronymic surname meaning "son of Tom (or Thomas)", itself derived from the Aramaic תום or Tôm, meaning "twin". There are many varied surname spellings, with the first historical record believed to be found in 1252. Thomsen is uncommon as a given name.
People with the surname Thomsen include:
Britta Thomsen (born 1954), Danish politician and member of the European Parliament
Cecilie Thomsen (born 1974), Danish actress and model
Christian Jürgensen Thomsen (1788–1865), Danish archaeologist
Claus Thomsen (born 1970), Danish former professional footballer
Ebba Thomsen (1887–1973), Danish actress
Finn Thomsen (born 1955), Danish motorcycle speedway rider
Fred Thomsen (1897–1986), American college football player and coach
Grímur Thomsen (1820–1896), Icelandic poet and editor
Grover C. Thomsen, Danish-American chemist who created the soft drink Big Red (drink) in 1937
Gunnar H. Thomsen, Faroese musician and member of Týr (band), a Faroese heavy metal band active 1998–present
Hans Peter Jørgen Julius Thomsen (1826–1909), Danish chemist noted in thermochemistry for the Thomsen–Berthelot principle
Hasse Thomsén (1942–2004), Swedish heavyweight boxer
Ib Thomsen (born 1961), Norwegian politician
Iris Thomsen (born 1987), Danish dancer
Knud Vad Thomsen (1905–1971) Danish composer
Linda Chatman Thomsen (born 1954), American lawyer and public servant
Lynn Thomsen (born 1964), former American football player
Mads Thomsen (born 1989), Danish former professional football forward
Mark A. Thomsen (born 1956), American operatic tenor
Marlene Thomsen (born 1971), Danish former badminton player
Martha Thomsen (born 1957), American model
Martinus Thomsen (1890–1981), Danish writer and mystic
Moritz Thomsen (1915–1991), American farmer and writer
Philipp Thomsen, a perpetually drunken Kriegsmarine submarine commander in the book and film Das Boot
Poul Mathias Thomsen, Danish economist working for the International Monetary Fund
Søren Ulrik Thomsen (born 1956), Danish poet
Stu Thomsen (born 1958), American former bicycle motocross (BMX) racer
Sven Thomsen (1884–1968), Danish competitive sailor
Tina Thomsen (born 1975), Danish-born Australian actress
Tue Bjørn Thomsen (1972–2006), Danish professional boxer
Ulrich Thomsen (born 1963), Danish actor
Vern Thomsen, American college football coach, 1983–1987
Vilhelm Thomsen (1842–1927), Danish linguist