Peter Carl Friedrich Geyer (1802–1889) was a German entomologist who wrote and illustrated various supplements to Jacob Hübner's works on Lepidoptera.^[1]

Carl Geyer was by profession an artist. He is not to be confused with Karl Andreas Geyer (1809–1853), a botanist and plant collector.

• Evenhuis, N. L. 1997 Litteratura taxonomica dipterorum (1758–1930). Volume 1 (A-K); Volume 2 (L-Z). Leiden, Backhuys Publishers.

• Carl Geyer (1796–1841) mentioned in Jacob Hübner's biography: Neue Deutsche Biographie, vol. 9, 1972, p. 720 (in German)