Cladonia cornuta or the bighorn cup lichen is a species of fruticose, cup lichen in the family Cladoniaceae. It was first described as a new species by Swedish lichenologist Carl Linnaeus in his seminal 1753 work Species Plantarum. German biologist Georg Franz Hoffmann transferred it to the genus Cladonia in 1791. The lichen has a distribution that is circumpolar, boreal, and arctic. It has also been recorded from the Southern Hemisphere. In North America, Cladonia cornuta is colloquially known as the bighorn Cladonia.