Marianne Karlsmose (born 6 June 1973) was the leader of a Danish political party, the Christian Democrats (Kristendemokraterne) from 2002 to 2005. When she succeeded Jann Sjursen in 2002 she led an invigoration process of the party was one of the drivers for a name change of the party from the somewhat archaic name "Kristeligt Folkeparti" to the more modern "Kristendemokraterne". At the general election in 2005, the party did not pass the general threshold of two percent of the votes and it lost its seats in the Danish parliament Folketinget. As a consequence, Marianne Karlsmose stepped down and was succeeded by Bodil Kornbek.
She is married to Birger Nielsen. They have two children. Karlsmose graduated from the (Fredericia Amtsgymnasium) high school in 1992. She received a master's degree in history and politics from the University of Aarhus in 2001. Karlsmose is also a high school teacher at the Christian High School in Ringkøbing. .