Michele Stefano de Rossi (30 October 1834, Rome - 23 October 1898, Rocca di Papa) was an Italian seismologist. He was a younger brother to archaeologist Giovanni Battista de Rossi (1822-1894).
He received his education at the University of Rome, and during his subsequent career conducted research in the fields of archaeology, paleontology, geology, vulcanology and seismology. He studied the topography of catacombs, and collaborated with his brother onLa Roma sotterranea cristiana (1864-1877).
In the 1870s he developed a "seismic scale" to reflect varying levels of earthquake intensity. Meanwhile in Switzerland, independent of Rossi, limnologist François-Alphonse Forel (1841-1912) created a similar seismic scale. When the two scientists became aware of each other's work, a combined effort resulted in the Rossi–Forel scale for determining the intensity of earthquakes.
In 1874 he founded the Bullettino del Vulcanismo Italiano, a journal dedicated to the study of volcanoes and earthquakes.