Ophiocordyceps is a genus of fungi within the family Ophiocordycipitaceae. The widespread genus, first described scientifically by British mycologist Tom Petch in 1931, contains about 140 species that grow on insects. Anamorphic genera that correspond with Ophiocordyceps species are Hirsutella, Hymenostilbe, Isaria, Paraisaria, and Syngliocladium.