Pierre-Paul Grassé (November 27, 1895, Périgueux (Dordogne) – July 9, 1985) was a French zoologist, author of over 300 publications including the influential 52-volume Traité de Zoologie. He was an expert on termites and one of the last proponents of neo-Lamarckian evolution.
Grassé began his studies in Périgueux where his parents owned a small business. He went on to study medicine at the University of Bordeaux and studied biology in parallel, including the lectures of the entomologist Jean de Feytaud (1881–1973). Mobilized during World War I, he was forced to interrupt his studies during four years. By the end of the war he was a military surgeon.
Grassé continued his studies in Paris, focusing exclusively on science. He obtained his Licence in Biology and frequented the laboratory of biologist Étienne Rabaud (1868–1956). He abandoned his preparations for the agrégation to accept a position as professor in the École Nationale Supérieure Agronomique de Montpellier (1921), where the department of zoology was led by François Picard (1879–1939). There he frequented several phytogeographers like Charles Flahault (1852–1935), Josias Braun-Blanquet (1884–1980), Georges Kuhnholtz-Lordat (1888–1965) and Marie Louis Emberger (1897–1969). He became the assistant of Octave Duboscq (1868–1943) who oriented the young Grassé toward the study of protozoan parasites. After the departure of Duboscq to Paris, Grassé worked for Eugène Bataillon (1864–1953) and there discovered techniques for experimental embryology.