It's likely a combination of factors:
* The movie itself: The phrase "one, two, Freddy's coming for you" was first spoken by Freddy Krueger in the movie "A Nightmare on Elm Street" (1984).
* Fan culture: The rhyme likely evolved organically from the movie's popularity, with fans adding to and changing the original phrase.
* Pop culture: The rhyme has become such a popular part of horror movie lore that it's now practically a part of the collective subconscious.
So, while we can't point to a single person who "made" the rhyme, we can acknowledge that it's a product of the film's creative team, the fandom, and the larger pop culture landscape.