Which Leonardo painting is considered his only known male portrait?

Portrait of a Musician is considered Leonardo's only known male portrait painting. The unfinished work shows a young man in three-quarter view holding a folded sheet of music, and it is now housed in Milan's Pinacoteca Ambrosiana.

Leonardo probably painted it during his first Milanese period, in the mid-1480s. The face is highly finished, while much of the clothing and body remains less developed, giving the panel a striking contrast between precise psychological detail and unfinished passages. Its dark background and close attention to the sitter's expression connect it with Leonardo's later portraits.

The sitter's identity remains uncertain. For centuries he was thought to be Ludovico Sforza, Leonardo's powerful Milanese patron. A restoration in 1904–1905 uncovered the hand and sheet music, prompting scholars to identify him as a musician. Candidates have included Franchinus Gaffurius, Josquin des Prez, and Leonardo's friend Atalante Migliorotti, but no identification has been proven.

The painting's attribution has also had a complicated history, although modern scholars broadly accept at least the face as Leonardo's work. That combination of artistic certainty and historical uncertainty is why the portrait remains so intriguing.