The question has fueled countless schoolyard debates: Who would win if Superman and Batman fought one another?

Or if the creatures from Alien were matched against the trophy-hunting extraterrestrial from Predator? Or if Nightmare on Elm Street 's Freddy Krueger tried to terrorize Friday the 13th's Jason Voorhees?

In at least two of those cases, fans will find out what their fantasy match-ups look like. In what could herald a new trend, characters from separate franchises are being teamed up or made to battle on the big screen.

Actor Robert Englund has donned his bladed gloves for Freddy vs. Jason; several scripts for Aliens vs. Predator have been bandied about at 20th Century Fox; and Superman vs. Batman was shelved only recently after a titanic struggle to bring it to the silver screen.

"Elements of Hollywood are desperate, and they spot trends on Web discussion groups," Premiere senior editor and film critic Glenn Kenny said. "In particular Web sites where they discuss things like 'Could Alien take on Predator?'"

When word let out about a possible movie pitting the extraterrestrials against each other, fan sites overflowed.

"Alien and Predator fans must be some of the most in-depth and loyal movie fans out there, with the exception of maybe Star Wars and Star Trek fans," Pete O'Connor, Web designer for www.alienexperience.com, said from Ottawa, Ontario. "It's nuts."

A Fox spokesman said the movie is in such early stages it's impossible to comment on it.

Gary LeMel, president of Warner Bros. World Wide Music, is doing the score for the upcoming Superman and Batman movies, which replaced Superman vs. Batman. He said the D.C. Comics characters resonate with audiences.

"Superman has gone through so many different incarnations and all of them seem to be well-accepted," he said. "It's so cultural, it's man against the elements."

But Kenny was skeptical of "versus" movies.

"The whole idea is ludicrous," he said. "I'd be surprised if any of these produced a watchable film."

The movie that's furthest along, Freddy vs. Jason, from New Line, is an effort to milk two once-profitable franchises by combining two "characters who don't have a lot of currency left," he said. And though "fans have been drooling" about an Aliens vs. Predator flick for years, Kenny isn't expecting much.

"You devolve into making it a videogame," he said.

The exception, he said, was the defunct Superman vs. Batman movie, which had complementary characters with a long comic-book history of interactions.

Aliens and Predator fans defended the "versus" idea, though.

"Crossovers are often perceived as mere cash cows or last-ditch efforts to rejuvenate dying franchises," Ben Bradbury, director for Aliens vs. Predator News, said from Derby, England. "The Aliens vs. Predator franchise, being an exception, has firmly established itself over a long period of time as a viable franchise in its own right."

But being established can be difficult too, said LeMel who pointed out that meddling with America's superheroes Batman and Superman made studio execs nervous.

"God forbid it was done wrong, because you would wipe out both characters," he said.

And pitting two fan bases against each other is bound to disappoint some people. "Nobody is ever going to be satisfied with these things," Kenny said.

New Line Cinema senior vice president of production Stokely Chaffin said that though Jason and Freddy fans are distinct, there's a lot of "overlap."

"It's not like either fan base is out watching White Oleander when they're not watching their preferred franchise," she said. "Fans will profess to love one character over another, but by and large, the fans of one franchise have seen all the movies of the other."

And in defense of "versus" movies like Freddy vs. Jason, Chaffin brought up the granddaddy of them all, which didn't garner critical acclaim, but which many film buffs still recall fondly.

"It would be a clash of the titans reminiscent of Godzilla vs. King Kong," she said.