Many filmmakers have explored the sonic possibilities offered by experimental, avant-garde, and modernist music as it prospered in the mid-twentieth century. Fascinatingly, horror cinema, with all its eerie subject matter, has championed the use of experimental music in its films. Since the silent-film era, horror has stood much to gain by deviating from the normative film scoring standards developed in Hollywood. Filmmakers indebted to horror continually seek new sounds and approaches to showcase the otherworldly and suspenseful themes of their films. Numerous movies that challenged the status quo through transformative scoring practices achieved distinction among rival films. The rise of auteurist films in the 1950s further instigated experimental practices as the studio system declined and created a space for new filmmakers to experiment with aesthetic strategies. Film music scholarship has paid relatively little attention to the convergences between experimental concert music and horror scoring practices. This topic is crucial, especially horror’s employment of existing experimental music, as it has played a critical role in American filmmaking in the second half of the twentieth century. My thesis traces the relationship between horror cinema and experimental music. I survey the use of experimental music throughout the history of horror films and examine the scores for three films: William Friedkin’s The Exorcist (1973), Stanley Kubrick’s The Shining (1980), and Martin Scorsese’s Shutter Island (2010). With my case studies of these three films, I aim to fill a significant gap in film music scholarship, highlight the powerful use of experimental music textures and timbres and demonstrate this music’s significant role in cultivating new scoring practices that succeed in engaging, unnerving and shocking audiences of horror cinema.