Sordariomycetes is a class of fungi in the subdivision Pezizomycotina (Ascomycota). It is the second-largest class of Ascomycota, with a worldwide distribution that mostly accommodates terrestrial based taxa, although several can also be found in aquatic habitats. Some are phytopathogens that can cause leaf, stem, and root diseases in a wide variety of hosts, while other genera can cause diseases in arthropods and mammals.