This torso of a male figure represents Mars and is made by the sculptor Pietro Simone da Barga, after a model by Giambologna.

Pietro da Barga was an Italian sculptor, mainly working in bronze, but also using the materials stone, ivory and silver. He worked in Rome for Cardinal Ferdinando de' Medici (the later Ferdinando I, Grand Duke of Tuscany). The Cardinal was an enthusiastic collector of small-scale bronze replicas of sculpture pieces otherwise unobtainable. Da Barga often copied from antique sculptures, but also from contemporary ones, like here from Gaimbologna's Mars.
Representations of Mars in the 16th century often are hard to identify for Mars not always appears helmeted, which would have been his depiction in the ancient Roman way.

Mars is the god of war, one of the twelve Olympians. He was very brutal and aggressive and thus hated by everyone even his parents, Jupiter and Juno. The only exception was Venus, who fell in love with him. For the Romans he was the father of their founders Romulus and Remus.