Tough one, so many good ones...

I voted Gone With the Wind, the biggest box office hit of all time (adjusted for inflation). And yet, it is also a cult.

Of this list - Prime Cut...where is Rocky Horror? 200 Motels? Young Frankenstein?

Rocky Horror is there, all the most famous ones are on the list. Dracula didn't make the cut for me.

Young Frankenstein certainly deserves a mention, as do both of James Whale's Frankenstein movies.

AN Other

You mean you want an "other" option? I decided on a 15th title instead, these 15 are the most important and famous historically.

What criteria did you use to come up with that list?

???

Historical importance, excellence, and fame.

You've got the three most important underground films, all super 8
The five main masterpieces by the '70s most cult and underrated director, the great Michael Ritchie
You've got the most famous cult movie of all, Rocky Horror Picture Show
You've got the top two youth cult movies, a surfing film and a car cruising film with the greatest OST ever
You've got the strangest film ever, the disturbing and creepy "Eyes Without a Face"
You've got the biggest movie of all time in GWTW
You've got the greatest cop film ever with one of the coolest soundtracks and cult icon Clint Eastwood and cult director Don Siegel at his best.

I have a hard time seeing a lot of films on this list as being cult movies.

Gone With The Wind a cult movie?
Dirty Harry?
The Bad News Bears???
American Graffiti?
These were all box office smashes, not cult movies in any way.

Pink Flamingos-now that's a cult film.

My all-time favorite bad movie would have to be the original "Deep Throat".

I voted Rocky Horror, but you left out 2 of my big time favs:
Carnival Of Souls
Ladies & Gentlemen... The Fabulous Stains

"Phantom of the Paradise"

Since "American Graffiti" is one of my all-time favorite films, I picked that even though I'm not sure I'd classify it as a "cult movie"

Also forgot to mention Vincent Price's original version of The Last Man On Earth (I believe recently remade with Will Smith as I Am Legend??).

We can always quibble over films here or there, like the absence of Freaks, film noir, Un Chien Andalou, Ed Wood, Dr. Strangelove, maybe the Big Lebowski or Tarantino, or even personal favorites like Dark Star, Lonely Are The Brave, Repo Man or Amelie, but some of the films on your list don't even qualify under the book definition of a cult film. Plus, I find too much dominance by one director and an overwhelming emphasis on the '60s and '70s, which bypasses your definition of historical importance. The only movie you list before 1960, I believe, is Gone With The Wind. You even call Clint Eastwood a cult icon, yet ignore his enigmatic spaghetti cowboy for one of his most mainstream characters. Sorry, but I think "you're gonna need a bigger boat."

"Pink Flamingos - I don`t think it`s my best movie, but God knows the day I die it will be in the first paragraph of my obituary. It helped make trash more respectable. It lasted longer than I ever would have imagined. I still meet young kids who have just seen it and they react with the same disbelief that people did the first time. I`m proud of it. It was made to make fun of censorship laws at the time. All that has kind of faded. If I hadn`t done the scene where Divine ate dog shit, Johnny Knoxville would have done it in Jackass. The Jackass movies are the closest in spirit to Pink Flamingos than anything else."
— John Waters

Good point on both Ed Wood's movies & the Depp/Burton Ed Wood biopic.

The Blues Brothers is the best cult movie

I picked Rocky Horror. I have never before heard of Gone With the Wind or Dirty Harry being described as "cult movies".