Blasius Merrem (February 4, 1761 _ February 23, 1824) was a German naturalist.

Merrem was born at Bremen, and studied at the university of Gottingen under Johann Friedrich Blumenbach. He developed an interest in zoology, particularly ornithology. Merrem's work on bird classification was ahead of its time, particularly with regard to the separation of Ratites (running birds) and Carinates (flying birds).