Hydnellum is a genus of tooth fungi in the family Bankeraceae. Widely distributed in the Northern Hemisphere, the genus contains around 40 species. The fruitbodies of its members grow by slowly enveloping nearby bits of grass and vegetation. There is great variability in the form of Hydnellum fruitbodies, which are greatly influenced by environmental conditions such as rainfall and humidity, drying winds, and temperature. They are too tough and woody to eat comfortably. Several species have become the focus of increasing conservation concern following widespread declines in abundance.

The hydnoid fungi are a group of fungi in the Basidiomycota with basidiocarps producing spores on pendant, tooth-like or spine-like projections. They are colloquially called tooth fungi. Originally such fungi were referred to the genus Hydnum, but it is now known that not all hydnoid species are closely related.