Fontainea is a genus of plants under the family Euphorbiaceae. It comprises 9 species, found from Australia (6 spp.), New Caledonia and Vanuatu (1 sp.), and Papua New Guinea (2 spp.).
One species, F. oraria, the coast fontainea, is known only from 10 living plants growing on private property near Lennox Heads in northern New South Wales, Australia. Its status is highly endangered.