Ferdinand Carl Valentin Haecker (15 September 1864 – 19 December 1927) was a German zoologist, reader at Freiburg University from 1892. In 1900, he became professor at the University of Applied Sciences Stuttgart and in 1909 at Martin Luther University of Halle-Wittenberg. He was president of the Deutsche Zoologische Gesellschaft from 1922. He died unexpectedly from a stroke.

Haecker's contributions span the fields of ornithology, plankton (Radiolaria) cell biology, developmental physiology, genetics (where he established the subfield of phenogenetics). He also published a historical treatise on Goethe's work on morphology.

  • Rudolf Haecker: Das Leben von Valentin Haecker. in: Zoologischer Anzeiger, Band 174, Heft 1/1965, pp. 1–14, ISSN
  • Georg Uschmann: Haecker, Ferdinand Carl Valentin. In: Neue Deutsche Biographie (NDB). Band 7, Duncker & Humblot, Berlin 1966, ISBN 3-428-00188-5, 427 f.
  • Hans-Albrecht Freye: Valentin Haecker 1864 bis 1927. Leben und Werk. in: Hercynia, Band 2, Heft 3/1965, 326–337, ISSN
  • Haecker, Valentin Carl Ferdinand, in Jürgen Dietrich Kurt Kiefer: Bio-bibliographisches Handbuch der Akademie Gemeinnütziger Wissenschaften zu Erfurt. Akademie Gemeinnütziger Wissenschaften zu Erfurt, Erfurt 2005, ISBN 3-932295-61-7, 234.