Crittendenia is a genus of lichenicolous (lichen-dwelling) fungi in the monogeneric family Crittendeniaceae. The genus was circumscribed in 2021 to contain two species, C. lichenicola, and the type, C. coppinsii; these species were previously classified in the genus Chionosphaera. An additional 16 species were added to the genus the following year. The genus name honours British lichenologist Peter Crittenden.
Characteristics of Crittendenia include the tiny synnemata-like basidiomata, clamp connections, and aseptate tubular basidia from which 4–7 spores discharge passively, often in groups. The genus was originally considered to be of uncertain classification in the Agaricostilbomycetes; the family Crittendeniaceae was proposed in 2022 to contain the genus following molecular phylogenetic investigation.