User blog:Lamango/I found it.

I found the source of Tsuburaya inspiration to make the Ultraman series. Giant humanoid vs monster. He did it in 1965 with American monster, Frankenstein's beast, against beloved Toho monster, Baragon. The fight is so fast paced and has some great moments. Sure, Frankie's Monster doesn't have the height, beams and powers of an Ultra, but we can safely assume this played a part in the Ultraman fight scenes. I just gave this movie a re-watch after three years, both American dubbed, Japanese subbed and even the Japanese Audio Comentary. And it's so easy to see why Humanoid vs Monster took off like it did after this film. The fight was pretty well done.