Where does the violence at the heart of modern masculinity come from? From action movies to video games to sports culture, why is so much about being a man connected to violent competition? The story of the marketing of masculinity - whether as a lone hero or as a devoted husband--is the story of the Byronic Hero's journey through the nineteenth century. The Byronic hero's history is traced through authors as different as Lord Byron and Jane Austen, George Eliot and Sir Arthur Conan Doyle, Rudyard Kipling and Oscar Wilde. Much more than a literary genealogy, the history of the Byronic hero and its heir, romance masculinity, outlines the radical changes nineteenth and early twentieth-century masculinity undergoes during the rise of the middle-class, the upheavals of industrialization, the demands of global competition, and finally the price of empire. From political and sexual revolutionary in the Regency, to ideal Victorian husband, to a weaponized servant of the state in the years running up to World War I, the Byronic hero and its afterlife as a romance masculinity are still with us in more ways than just action heroes like Sherlock Holmes and James Bond. It tells us something about what makes men - men.