10. King Kong Vs. Frankenstein
It never actually happened - but it was animator Willis O'Brien's blueprint project for a new Kong film in the early 1960s. Hawked to Toho Films in Tokyo, prolific producer of the kaiju eiga monster movies, it seemed to subdivide into two movies: Frankenstein Conquers The World (1965), and Prometheus Vs. King Kong (after The Modern Prometheus, subtitle of Mary Shelley's Frankenstein), which in turn was changed again to