Opalina (so named by J. E. Purkinje and G. Valentin), is a genus of Protozoa found in the intestines of frogs and toads. It is without a mouth or contractile vacuole, covered with nearly equal flagelliform cilia, and possessing numerous nuclei, all similar. All the species are parasitic in cold-blooded vertebrates. Its body is leaf like. Cytostome is absent and nutrition is saprozoic.

Opalina is a girl's name of Indian / Hindu origin and means a Precious Stone. Taken from opal (a semiprecious gemstone which reflects light in a dazzling display of colors), which is ultimately derived from the Sanskrit word upala (precious stone, jewel). Variations of this name include Opal, Opale, Opala, Opalah, Opalia, Opaline, Opalyn, Opalyna, Opalynah, Opalyne.