Sigismund Wilhelm Koelle or Kölle (July 14, 1820[1] – February 18, 1902) was a German missionary working on behalf of the London-based Church Missionary Society, at first in Sierra Leone, where he became a pioneer scholar of the languages of Africa, and later in Constantinople (Istanbul). He published a major study in 1854, Polyglotta Africana, marking the beginning of serious study by Europeans of African languages.