Thaxterogaster is a genus of fungi in the family Cortinariaceae.

The Cortinariaceae are a large family of gilled mushrooms found worldwide, containing over 2100 species. The family takes its name from its largest genus, the varied species of the genus Cortinarius. Many genera formerly in the Cortinariaceae have been placed in various other families, including Hymenogastraceae, Inocybaceae and Bolbitiaceae.