The dissertation is the first study of heroic portraiture in Italy in the sixteenth century. With the term heroic, which is presented and justified in the introduction to the thesis, I qualify independent portraits in all media in which the sitter is represented in the guise of a mythological, historical or religious figure, like a god or a biblical character. These portraits, known from various studies as allegorical, historié, composite, or augmented have never been analysed as a genre and their function has so far been obscure. The thesis introduces the term heroic because the portraits are connected with the Aristotelian notion of heroic virtue, which found enormous currency during the Renaissance and shaped the cultural and artistic world of the artists and their subjects. The thesis is divided into three main chapters. The first is dedicated to Venetian heroic portraits from the first half of the sixteenth century, in particular portraits of ladies and gentlemen in the guise of saints and biblical figures, and portraits of Dominican friars in the guise of Dominican saints. The second chapter is dedicated to the heroic portraits of Cosimo I de’ Medici, Duke of Florence, from his election in 1537 to his death in 1574. One section analyses also the portraits of the Genoese ruler Andrea Doria as Neptune, comparing the use of heroic imagery by both rulers at key moments in the establishment of their regimes. The third main chapter deals with heroic portraits of Bolognese intellectuals and patricians from the late sixteenth century; a rich section is dedicated to female heroic portraiture of Bolognese ladies as a way to communicate cultural refinement and moral values related to post-Tridentine norms of decorum.