P. Marie Thomsen (c.1814 – after 1889) was a pioneering Norwegian photographer who together with Christian Olsen (1813–1898) opened a photographic studio in Christiania (now Oslo) in May 1859. By 1865, she had dissolved her partnership with Olsen. That year she left her studio and her archives to Mimi Frellsen who had earlier served an apprenticeship with her.[1] [2]