Australonycteris is an extinct and monotypic genus of microchiropteran bat with the single species Australonycteris clarkae. The species is known from fragmentary remains found at the Murgon fossil site, in south-eastern Queensland, dating to the early Eocene, 54.6 million years ago. It is the oldest bat from the Southern Hemisphere and one of the oldest bats in the world, and inhabited forests and swampy areas, with a diet of insects and probably even small fish.