The process of selecting which screenplays to “greenlight”, or fully finance for production, is one of the most important stages in film production since the cost of acquiring and developing a screenplay is negligible compared to the later costs of producing, marketing and distributing a film. Despite this, very little is known about the contribution that elements of a film’s narrative make towards a film’s box office performance. In this thesis I examine the widely-received idea that “primal” aspects of film protagonists, including their personality traits, motivations and emotions, contribute significantly towards a film’s universal appeal as measured by worldwide ticket sales. I also interrogate the proposition that certain protagonist qualities are universally liked by audiences. Drawing on models of human behaviour advanced by evolutionary psychologists, I propose that an evolutionary framework will illuminate our understanding of film protagonists and their associated audience appeal. I report the development of a new instrument to assess differences in film protagonists’ emotions, motivations and character traits, and then use this questionnaire in five studies. Through analysis of 170 films exhibited in North America and China between 1995 and 2014, I find the questionnaire to be comprehensive. I also find that the psychological attributes of a film protagonist may be used to predict the territory in which a film is preferred, whether a film is likely to rank in the top ten at the North American box office and whether a high-budget film is more likely to be a global box office hit or flop. These findings are consistent with evolutionary theories, which would suggest that screen characters’ traits, motivations and emotions are writers’ emulations of universal adaptations to evolutionary selection pressures, reshaped through aesthetic and cultural processes. I conclude that an evolutionary framework offers useful insights into which aspects of film protagonists may be universally liked. It also reveals cross-cultural variation in audiences’ preferences for films with protagonists with certain attributes. Finally, I argue that this knowledge may benefit the industrial greenlighting process and screenwriting pedagogy.