Tilletia is a genus of smut fungi in the Tilletiaceae family. Species in this genus are plant pathogens that affect various grasses. Tilletia indica, which causes Karnal bunt of wheat, and Tilletia horrida, responsible for , are examples of species that affect economically important crops. The widespread genus contains about 175 species. The genus was circumscribed by Edmond Tulasne and Charles Tulasne in Ann. Sci. Nat. Bot. ser.3, vol.7 on page 112 in 1847. The genus was named after a agronomist from France, Mathieu Tillet (1714–1791).