Horror is a movie genre that has many sub-genres within it. You have your slasher horrors, your monster horrors, your splatter horrors, body horrors, and psychological horrors, all of which play on different fears we have in different ways. One intrepid lover of the genre was looking for examples of something a little more left-field, musical horrors.
Musical theatre or musical films are a genre of their own whilst also being able to adapt to many other genres within storytelling. You can take almost anything and turn it into a musical really. Les Misérables is a historical drama musical, Funny Girl is a biographical comedy musical, Chicago is a crime musical, and hell West Side Story is a musical retelling of Shakespeare’s Romeo and Juliet set in 1950s New York. It stands to reason then that there are musicals that fall within the horror genre too.