Melanogaster ("black-bellied") may refer to the following organisms:
- Genera:
- Melanogaster (fungus), a genus of false truffles
- Melanogaster (fly), a genus of hoverflies
- Species:
- Drosophila melanogaster, a species of fruit fly, widespread and also important in research
- Acheilognathus melanogaster, a species of brackish-freshwater ray-finned fish in Japan
- Anhinga melanogaster, the Oriental darter (snakebird), a water bird of tropical South Asia and Southeast Asia
- Turnix melanogaster, the black-breasted buttonquail (a rare bird in Australia)