This iconic Frankenstein poster not only set the tone for a decade that saw the rise of Universal's monster movies, it also pushed into consciousness an image of Frankenstein's monster that has remained the go-to look for him to this day.
This decade belonged to horror, and with Universal placing particular emphasis on the actual monsters, the genre's bad guys became visually recognisable in a way that laid the foundation for horror going forward. If it were not for posters like this one, positioning the monsters in a way that had previously only been reserved for stars or heroes, we would not have the likes of Freddy, Jason and Leatherface in later years.
Honourable Mentions: Dracula, The Bride of Frankenstein