Jean-Lou Justine (born 1955), French parasitologist and zoologist, is a professor at the National Museum of Natural History in Paris, France, and a specialist of fish parasites and invasive land planarians.

He passed his PhD in 1980[2] and his Doctorat d'État (State doctorate) in 1985,[3] both in the University of Montpellier, under the supervision of Professors Xavier Mattei and Louis Euzet.

Justine is the curator of the parasitic worms in the National Museum of Natural History in Paris, France,[1] [4] and, since 2013, a deputy-director the Institute of Systematics, Evolution and Biodiversity (ISYEB),[1] one of the largest units in the MNHN.

[8][9][10][11] Justine has published more than 250 papers since 1981 [12] [13] and described more than one hundred new species,[14] which are all parasitic animals belonging mainly to the Nematoda and Monogenea, and also Digenea, Cestoda, and Crustacea.

[39] Among the Monogenea, Cichlidogyrus jeanloujustinei Rahmouni, Vanhove & Šimková, 2017 [40] has been named after him, as well as four species of the genus Pseudorhabdosynochus, namely Pseudorhabdosynochus justinei Zeng & Yang, 2007,[41] P. enitsuji Neifar & Euzet, 2007 [42] (an anagram of justinei), P. jeanloui Knoff, Cohen, Cárdenas, Cárdenas-Callirgos & Gomes, 2015,[43] and P. justinella Kritsky, Bakenhaster & Adams, 2015.