The Creeper "is an ancient demon who feeds on human beings for twenty-three days every twenty-third Spring."
http://en.wikipedia.org/wiki/The_Creeper_%28Jeepers_Creepers%29
So I guess he is a demon. Cool movie, the first one that is. The second blew, though it was cool to see him with more dimension (in essence, more of his face, how he stalked his prey, how he chose to kill them, et cetera). I wish they'd kept it at one movie, though, b/c it rocked.