The Laboulbeniales is an order of Fungi within the class Laboulbeniomycetes. They are also known by the colloquial name, labouls. The labouls include over 2000 species of obligate insect ectoparasites, with cellular thalli. They typically do not kill their hosts, although they may impair host fitness if the level of infestation is high. Foundational work on the Laboulbeniales was completed by the American mycologist Roland Thaxter (1858–1932), particularly in a five-volume illustrated series (1896–1931).