Amanita muscaria, commonly known as the fly agaric or fly amanita, is a poisonous and psychoactive basidiomycete fungus, one of many in the genus Amanita. Native throughout the temperate and boreal regions of the Northern Hemisphere, Amanita muscaria has been unintentionally introduced to many countries in the southern hemisphere, generally as a symbiont with pine plantations, and is now a true cosmopolitan species. It associates with various deciduous and coniferous trees.
The quintessential toadstool, it is a large white-gilled, white-spotted, usually red mushroom, one of the most recognisable and widely encountered in popular culture. Several subspecies with differing cap colour have been recognised, including the brown regalis (considered a separate species), the yellow-orange flavivolvata, guessowii, formosa, and the pinkish persicina. Genetic studies published in 2006 and 2008 show several sharply delineated clades that may represent separate species.