Inocybe lacera, commonly known as the torn fibrecap, is a poisonous species of mushroom in the genus Inocybe. Its appearance is that of a typical "little brown mushroom": small, brown and indistinct. It is distinguishable by its microscopic features, particularly its long, smooth spores. There are several documented subspecies in addition to the main I. lacera var lacera, including the dwarf form I. lacera var. subsquarrosa and I. lacera var. heterosperma, found in North America.

Found in Europe and North America, it typically grows in autumn in mixed woods, favouring sandy soil. As with many other species of Inocybe, I. lacera contains the poisonous chemical muscarine which, if consumed, can lead to salivation, lacrimation, urination, defecation, gastrointestinal problems and vomiting.