Karl Theodor Ernst von Siebold, German physiologist and zoologist (b. 1804)
Prof Karl (Carl) Theodor Ernst von Siebold FRS(For) HFRSE (16 February 1804 – 7 April 1885) was a German physiologist and zoologist. He was responsible for the introduction of the taxa Arthropoda and Rhizopoda, and for defining the taxon Protozoa specifically for single-celled organisms.