Dorothy Olga Johansen (19 May 1904 – 13 December 1999) was an American historian of the Pacific Northwest.
Johansen was a director of the Oregon Historical Society and a member of the Pacific Northwest Quarterly and America: History and Life advisory boards.
A year prior, she wrote Empire of the Columbia: A History of The Pacific Northwest,[2] with Charles M. Gates.
In 1959 Johansen wrote Robert Newell’s Memoranda and Voyage of the Columbia: Around the World with John Boit, 1790–1793.
In 1966 she was president of the Pacific Coast branch of the American Historical Association.