Ernest Frederick Waldemar Albert Mangelsdorf (December 15, 1856 - January 23, 1925) was a German American draftsman. Born in Germany, Mangelsdorf arrived in the United States in 1883. He worked as a draftsman for Silas Farmer in Detroit throughout the 1880s until at least the early 1890s when he started working for the U.S. government in the Engineeer's office also as a draftsman. Mangelsdorf died of pneumonia in Detroit on January 23, 1925. He married Katherine Leefe (1871 - 1948) with whom he had one daughter, Marie Emilie (1902 - 2002).