How do you surprise someone who's seen it all — aliens who snatch bodies and aliens with dreadlocks and aliens who bloodily birth themselves from your stomach and aliens who phone home and aliens who eat cat food and great big blue aliens with tails they use for sex?

Forget about the decades of classic extraterrestrial flicks that stream daily on TV, tablets and desktops. This year alone, movies like "Battle: Los Angeles," "Super 8," "Green Lantern" and "Transformers: Dark of the Moon" have hit the big screen, each trying to deliver not only eye-popping visuals but the post-credits comment between friends, "Damn, dude, have you ever seen something like that?"

The answer, all too often and quite understandably, is, "Yes, yes, I have." That's the challenge "Cowboys & Aliens" director Jon Favreau faced as he sought to bring alien baddies to the Old West for a genre mash-up that hit theaters Friday (July 29). Favreau, though, counts himself lucky that he was able to lean on some of the most-established sci-fi players in Hollywood for help. The cinematic result is a race of aliens that land in a down-on-its-luck mining town, start to kidnap residents and eventually reveal themselves as extraterrestrial superfreaks on par with anything we've seen at the theater in recent years.

Earlier this month in Montana, Favreau talked with MTV News about what makes a great big-screen alien, the special-effects decisions that helped his filmmaking process and the advice Steven Spielberg and Guillermo del Toro gave him along the way. (Beware of spoilers below.)

"When you set out to make a movie like 'Cowboys & Aliens,' if you just play it as one joke for the whole movie, you're in trouble," Favreau explained. "You run out of gas after about the length of an 'SNL' sketch. So we really wanted to find an approach that could bear out a whole story. Part of it was identifying what kind of alien movie to make and what kind of cowboy movie to make."

The answer to the alien question was to reach back to classics of the '70s and '80s, before CG glam overtook practical effects as the preferred method of creating otherworldly creatures. "The alien movies I like the most are the ones I grew up with," he said. "It was the pre-CG, almost verging on horror versions of alien films, like 'Alien,' 'Aliens,' 'Predator' and all the Spielberg stuff, and I include 'Jaws' in that, too. They were all the same kind of movie.

"It was before you had computer effects, so you had to, through lighting and mystery and music, slowly reveal the creature. That technique has some somewhat been lost now, thanks to CGI. Even though we have CGI creatures eventually, we do use animatronics and we do use lighting and all the old techniques to reveal them."

The aliens in "Cowboys" have landed in an Arizona town to mine for gold — a metal as precious to humans as it is to these space travelers. What's truly cool about them is their transformative quality: Their faces move and shift to expose layers below, and their bodies open up to unleash hidden, gooey hands. Gross and fascinating and scary, all at once. That's exactly what Favreau was hoping to accomplish.

" 'Predator' and 'Alien': What was fun about those films is, as you saw the creatures, more and more layers were revealed, whether it was armor coming off with 'Predator' [and] weaponry, or in the case of 'Alien,' with the second set of teeth or the metamorphosis that it did from its egg state to the face-hugger to whatever that larval phase was when it busts out of your chest and finally into the big [creature]," he said. "It's the shape-shifting quality of the aliens that I thought was really cool. We wanted to maintain some mystery and surprises with our creature."

To create those surprises, Favreau not only depended on his team of artists and effects masters, but on Spielberg and del Toro. "[Spielberg] was very involved with certain aspects of it preproduction, and one of those aspects was the alien design, because he's been involved with so many," he said. "And now seeing 'Falling Skies' and seeing 'Super 8,' I see that he was not just involved with his own films, but other films and projects he's been producing and overseeing. He had a lot of specific insight into what things were important.

"And Guillermo del Toro, I also know him, and he's masterful," Favreau added. "He always said you've got to get the silhouette right first and then you got to get the color right and then you got to get the detail right, in that order. He's actually somebody who helped out and came in the editing room. I was showing him our animatronic work, because he's very picky about that stuff, and when I knew it passed his muster, I felt very good."

Check out everything we've got on "Cowboys & Aliens."

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