A total of 22 species of lichenicolous fungi and three lichens are reported on Stereocaulon species and discussed. Lichenopeltella stereocaulorum sp. nov., Lichenosticta dombrovskae sp. nov. and Odontotrema stereocaulicola sp. nov. are described from Stereocaulon. Arthonia stereocaulina, Opegrapha stereocaulicola, Rhymbocarpus stereocaulorum and Sphaerellothecium stereocaulorum are reported new to North America (except Greenland); Endococcus nanellus is new to Kazakhstan, Alaska and Greenland; Arthonia stereocaulina and Opegrapha stereocaulicola are new to Svalbard; Catillaria stereocaulorum, Cercidospora stereocaulorum, Lasiosphaeriopsis stereocaulicola, Polycoccum trypethelioides and Taeniolella christiansenii are new to the U.S.A.; Catillaria stereocaulorum and Niesslia peltigericola are new to the Canadian Arctic; Lasiosphaeriopsis stereocaulicola and Taeniolella christiansenii are new to British Columbia; and Catillaria stereocaulorum is new to Mongolia. Anzina carneonivea, Endococcus rugulosus s. l., Niesslia peltigericola, Phaeosporobolus alpinus and Protothelenella sphinctrinoidella are newly documented on Stereocaulon. Seventeen species of Stereocaulon are new hosts for various lichenicolous fungi. A key to the 39 species of fungi and lichens known to occur on Stereocaulon is provided. Study of the host relationships of lichenicolous fungi on Stereocaulon does not support a close relationship between the crustose and fruticose species of the genus. Terricolous arctic species of Stereocaulon with more solid thallus structure are more frequently colonized by fungi when compared to species with lax thalli