Amandus Johnson (October 27, 1877 – June 30, 1974) was an American historian, author and founding curator of the American Swedish Historical Museum. He is most associated with his epic two volume history The Swedish Settlements on the Delaware 1638-1664, which was also published in Swedish as Den första svenska kolonien i Amerika (1923).
Amandus Johnson was born in Långasjö, a small village now located in the municipality of Emmaboda of Kalmar County in the historic Swedish province of Småland. He was three years old at the time his family came to Rice Lake (CDP), Minnesota. Johnson attended Gustavus Adolphus College from which he graduated in 1904 with a baccalaureate degree in English literature. During 1904–1905, Johnson continued to study at the University of Colorado where he took a master's degree. He won fellowships at the University of Pennsylvania where he took his Ph.D. in 1908.
In 1908, Johnson was one of the co-founders of the Swedish Colonial Society, whose members traced their ancestry to the pre Revolutionary War Swedish colonists. Johnson served as instructor and later assistant professor of Scandinavian Languages at the University of Pennsylvania from 1910 to 1921. After serving as President of the Historical Section of the American Division of the Gothenburg Exhibition in Gothenburg, Sweden, in 1921 Johnson accepted the post of Director of the African Educational Expedition to Angola, during 1922–1924. In the years after the expedition, Johnson published a Kimbundu English Portuguese dictionary and a narrative about his travels.