Pennywise the clown sure is terrifying. However, this Stephen King creation is much more than it seems. This horrifying monstrosity feeds on your fears, but the first It movie didn't delve much deeper into the character than that. However, It: Chapter 2--which comes to theaters on September 6--gives the audience the character's full backstory, and it's pretty crazy. In the video above, we detail just who and what Pennywise is.Warning: Spoilers for It: Chapter 2 are above.