Karl Gegenbaur, German anatomist and academic (d. 1903)
Karl Gegenbaur (21 August 1826 – 14 June 1903) was a German anatomist and professor who demonstrated that the field of comparative anatomy offers important evidence supporting of the theory of evolution. As a professor of anatomy at the University of Jena (1855–1873) and at the University of Heidelberg (1873–1903), Karl Gegenbaur was a strong supporter of Charles Darwin's theory of organic evolution, having taught and worked, beginning in 1858, with Ernst Haeckel, eight years his junior.

Gegenbaur's book Grundzüge der vergleichenden Anatomie

(1859; English translation Elements of Comparative Anatomy by Francis Jeffrey Bell, 1878) became the standard textbook, at the time, of evolutionary morphology, emphasizing that structural similarities among various animals provide clues to their evolutionary history. Karl Gegenbaur noted that the most reliable clue to evolutionary history is homology, the comparison of anatomical parts which have a common evolutionary origin.Gegenbaur had been a student of Albert von Kölliker, Rudolf Virchow, Heinrich Müller and Franz Leydig (1821–1908).