Thielavia is a genus of fungi in the family Chaetomiaceae. Circumscribed by German botanist Friedrich Wilhelm Zopf in 1876, Thielavia is a teleomorph of Myceliophthora. Collectively, the genus is widely distributed, and according to a 2008 estimate, contains 31 species. Thielavia heterothallica an T. terrestris can cause infections in humans.