冬虫夏草（学名：Cordyceps sinensis (Berk.) Sacc.），是中国历史中传统的名贵中药材，是由肉座菌目麦角菌科麦角菌属的冬虫夏草菌寄生于高山草甸土中的蝠蛾幼虫，使幼虫身躯僵化。并在适宜条件下，夏季由僵虫头端抽生出长棒状的子座而形成，即冬虫夏草菌的子实体与僵虫菌核（幼虫尸体）构成的复合体。目前主要认为冬虫夏草的真菌无性型为中国被毛孢（学名：Hisutella sinensis）。冬虫夏草主要产于中国大陆青海、**、四川、云南、甘肃、贵州等省及自治区的高寒地带和雪山草原。

冬虫夏草「补肺益肾，止血化痰，秘精益气」。

Cordyceps /ˈkɔːrdəsɛps/ is a genus of ascomycete fungi (sac fungi) that includes about 400 species. All Cordyceps species are endoparasitoids, parasitic mainly on insects and other arthropods (they are thus entomopathogenic fungi); a few are parasitic on other fungi. Until recently, the best known species of the genus was Cordyceps sinensis, first recorded as yartsa gunbu in Nyamnyi Dorje's 15th century *****an text An ocean of Aphrodisiacal Qualities. In 2007, nuclear DNA sampling revealed this species to be unrelated to most of the rest of the genus' members; as a result it was renamed Ophiocordyceps sinensis and placed in a new family, the Ophiocordycipitaceae.