Orthetrum pruinosum, the crimson-tailed marsh hawk, is a species of dragonfly in the family Libellulidae. It is a widespread species occurring from west India to Japan and south to Java and the Sunda Islands. It breeds in puddles, ponds and tanks. Three subspecies are recognized. A molecular phylogenetics study of Orthetrum dragonflies revealed that Orthetrum pruinosum is a cryptic species.