Gellertia is a monotypic genus of karyorelict ciliates in the family Geleiidae. It contains a single species, Gellertia heterotricha.
The genus is on average 400 üm long and 60 üm in width. It is characterized by a very simplified adoral infraciliature, reduced to a row of two dikinetids (whereas the genus Geleia shows long polykinetids).
The genus name is a taxonomic patronym honoring the protistologist József Gellért.