Meganeura monyi was a prehistoric insect of the Carboniferous period (300 million years ago), resembling and related to the present-day dragonfly. With a wingspan of more than 75 cm (2.5 ft) wide, it was the largest known flying insect species ever to appear on Earth. (The Permian Meganeuropsis permiana is another contender). It was predatory, feeding on other insects and even small amphibians.

Fossils were discovered in the Stephanian Coal Measures of Commentry in France in 1880; in 1885, French paleontologist Charles Brongniart described and named the fossil. Another fine fossil specimen was found in Bolsover, Derbyshire, in 1979. The holotype is housed in the Muséum National d'Histoire Naturelle, Paris.