Han Nijssen (1935– 2013)[1][2] was a Dutch ichthyologist.[3]
Nijssen was born in Amsterdam and obtained his PhD at the University of Amsterdam in May 1970 with the dissertation Revision of the Surinam catfishes of the genus Corydoras.[1] Later he was a curator at Zoölogisch Museum in Amsterdam. Nijssen worked extensively with fish from South America, and was the author of several species, e.g. Corydoras weitzmani and Corydoras xinguensis. Collaborating with Isaäc Isbrücker he described, among others, the group Hypancistrus and the species Hypancistrus zebra and Corydoras panda. He also collaborated with Sven O. Kullander.