Wilhelm Michaelsen

Wilhelm Michaelsen (born 9 October 1860 in Hamburg, Germany, died 18 February 1937) was a German zoologist. His principal contributions were to the study of Oligochaeta.

After finishing high school he studied mechanical engineering. He later returned to study natural sciences as a graduate student. In 1887 he commenced work at the Hamburg Zoological Museum, at first as a research assistant. He was later to become Hauptkustus (chief curator).

Though he also worked in the study of Tunicates and Polychaetes, Michaelsen was best known for his work on Oligochaeta. To that end, he travelled to southern regions of South America, Africa and Australia to investigate paleographic records of ancient Oligochaete distribution.