Medardo Rosso (21 June 1858, Turin, Italy – 31 March 1928, Milan) was an Italian sculptor. He is thought to have developed the Post Impressionism style in sculpture along with Auguste Rodin.

Medardo Rosso was born in Turin, Italy, in 1858, the son of the city stationmaster. Later his family moved to Milano (Milan). As a child Rosso played hookey from school to visit a monument mason who taught him to handle a chisel and hammer. This distressed and angered his parents. At the age of 23, after a period of military service as unsatisfactory as his home life, he enrolled at the Brera Academy in Milano, where he learned to draw classical statues and copy them in gesso.

But academic art appeared to him entirely artificial, unrelated to the world around him. Before long he helped to organize the Brera students into demanding life models for the drawing classes. As a result of his revolutionary behavior he was expelled from the school. He moved to Rome, where he lived in great poverty, sleeping among the ruins of the Colosseum.

To the end of his life Rosso battled unremittingly against the academicians. What absorbed, even obsessed, him was the problem of interpreting life itself. In 1882, some time before he saw any Impressionist paintings, he produced his fully impressionistic sculptures, The Street Singer and Lovers under the Lamplight. In 1884 some friends arranged an exhibition for him in Paris, where he lived for a time in a cheap boarding house. He also exhibited that year in Paris at the newly founded Salon des Independants. He met Edgar Degas and called on Auguste Rodin, who was interested in and indeed not uninfluenced by him. The sculptor and teacher Jules Dalou allowed him to work in his Paris studio.

In 1885 Rosso returned to Milan, but he never lost contact with Paris. During an open competition held in Milan for a funeral monument to the critic Filippo Filippi, Rosso, who had quickly finished his entry, set it up on the grave without waiting for the judges to announce their decision. On this occasion there was a great outcry against him, but by continuing to follow these tactics in galleries and exhibitions, he gradually wore down the resistance of the authorities.

In 1886 the writer Émile Zola bought a bronze by Rosso, who thereby gained a measure of celebrity. Auguste Rodin offered to exchange a torso of his own for Rosso's recent head of a laughing woman. Rosso's work, praised by Degas, always enjoyed greater esteem in France than in Italy. Nevertheless he had some influence on Italian painting and made a powerful impact on Italian sculpture, which had remained virtually static since the time of the Neoclassical Antonio Canova. His admirers have included the Futurists Carlo Carra and Umberto Boccioni, and the modern Milanese sculptors Giacomo Manzu and Marino Marini.

Rosso came closer, however, than any other sculptor has to the methods of the Impressionist painters. It was his constant concern to translate into solid sculpture the transitory effects of light. So by means of rough, spontaneous modeling he manipulated light and shade in such a way as almost to produce the effect of color. In this process the distinctive characteristics of his material played an increasingly important part. Indeed, his sense of the necessity for truth to materials became one of the ideals of 20th century art.

Rosso was able to maintain a studio in Paris and to hold a number of exhibitions. In 1896 he showed in London at the Goupil Gallery. He also had a success in New York. Toward the end of his life he suffered from diabetes and a malignant growth on the foot. He made few sculptures after 1900. He died on 31 March 1928, after the amputation of the affected leg.