What lesser-known cult films fit a midnight double bill and why?

[OliviaDT]

I'm putting together a midnight movie marathon for a local indie theater, and I want to feature a double bill of true cult classic films. I'm thinking of pairing something like "The Rocky Horror Picture Show," which has an active participatory tradition, with a more obscure, visually striking film like "Eraserhead" or "The Holy Mountain." What are some other lesser-known cult films that have developed a dedicated following over the years, and what do you think are the essential ingredients—whether it's midnight screenings, quotable dialogue, or sheer weirdness—that transform a box office flop into a lasting cult phenomenon?