You know it because it's happened to you.

You settle into your seat at you local multiplex, excited to see the latest movie starring your favorite actor. The lights dim, the projector kicks into action, the movie starts and then ... the person you came to see was barely in the film. Sometimes, the film is so good that you don't care or there's a reason why their role was limited. Other times, there's something a little more nefarious at work, and you realize that you've been tricked into seeing a movie by a marketing team who sold a supporting turn as a lead.

Their faces were on the poster. They were featured prominently in the trailer. But they had three scenes, tops.

Misleading film marketing like this has been around for decades. B-movies and exploitation pictures would shell out enough cash to get a former movie star to show up on set for a day or two, just to get their name on the poster. Sometimes the results are fine. Sometimes they're insulting.

[SPOILER WARNING: We discuss major plot points for films like 'Spring Breakers,' 'Seventh Son,' 'G.I. Joe: Retaliation' and more. Proceed with caution.]

  • 1

    Kit Harington in 'Seventh Son'

    Although the film doesn't actually arrive in theaters until early next year, the grand tradition of selling supporting roles as leads looks to continue with 'Seventh Son.' Aside from getting his own character poster, Harington also joined the Comic-Con 2013 panel alongside Jeff Brides, Ben Barnes and Antje Traue. As the 'Seventh Son' trailer suggests, Harington is barely in the film (watch the first 30 seconds or so), with the real starring part belonging to Barnes. However, Harington is a major character on HBO's 'Game of Thrones' and Barnes ... is not. From a marketing standpoint, it makes sense to emphasize the guy with the more recognizable face, but people looking for a movie starring Jon Snow should probably wait for 'Pompeii' instead.

  • 2

    Selena Gomez in 'Spring Breakers'

    Harmony Korine's 'Spring Breakers' was one of the most talked about films in recent memory, with much of the conversation focusing on James Franco's bizarre performance and the sexualization of former teen icons Vanessa Hudgens and Selena Gomez. Although the film's marketing centered around its four scantily clad female leads, the group of friends don't actually spend the entire film together. As the girls find their spring break vacation turning into a nightmare of violence and depravity, they begin to go home, one-by-one. Gomez is the first to go, never to be seen again. It's a moment that makes perfect sense for the character, but it remains odd to see one of the film's biggest selling points flee so abruptly.

  • 3

    Sean Penn in 'The Tree of Life'

    For an actor, signing on to act in a Terrence Malick film is like playing Russian roulette. You have a juicy role on the page and you film that juicy role and you have a chance that the juicy role will end up in the finished film. But there's also a strong chance that Malick will completely reinvent the film in post-production, cutting your character down to the bare minimum (and possibly out of the film entirely). We doubt Sean Penn would have agreed to appear in 'The Tree of Life' if he knew the finished film would reduce him to a minimal co-star, whose screen time was dwarfed by rays of sunlight, CGI dinosaurs and the young Hunter McCracken. With few lines and almost no bearing on the actual main storyline, Penn's job in the film is to look sad and tired as he remembers everything of real interest in the movie.

    Fox Searchlight
  • 4

    Jamie Foxx in 'Stealth'

    A funny thing happened when the action movie 'Stealth' began its marketing campaign: Jamie Foxx won an Oscar for 'Ray.' Suddenly, this silly movie about a robot plane whose artificial intelligence turns evil had an Academy Award winner in the cast, and the posters and trailers acted accordingly. Foxx received billing at the top of the poster alongside real leads Josh Lucas and Jessica Biel, and the trailers painted his character as the main star. So it must have been a huge surprise for audiences when his character bites the bullet halfway through the film, his true role as "guy whose death inspires the others to get revenge" revealed.

  • 5

    Channing Tatum in 'G.I. Joe: Retaliation'

    When 'G.I. Joe: Rise of Cobra' hit theaters, fans bemoaned Channing Tatum's lead performance as Duke. Why was this marble-mouthed meathead leading America's greatest team of heroes? The studio heard the complaints and went to fix it, making a sequel where Tatum was killed off in the opening scenes, letting a new cast take over the franchise. Alas, Tatum found his groove between 'G.I. Joe' films, discovering his sense of humor and leading two massive hits with 'Magic Mike' and '21 Jump Street.' The marketing tried to hide the fact that he was barely in the movie, but watching the newly delightful Tatum exit the movie in the opening act of 'G.I. Joe: Retaliation' is painful, especially since his banter with Dwayne Johnson is one of the film's highlights.

  • 6

    Arnold Schwarzenegger, Bruce Willis and Chuck Norris in 'The Expendables 2'

    The first 'Expendables' film offered one of the most disgusting bait-and-switches in movie history, featuring Arnold Schwarzenegger and Bruce Willis prominently in the trailers despite the fact that they only had a few lines and a single scene. It wasn't as bad in 'The Expendables 2,' but both actors have much smaller roles than the marketing would have you believe. Both show up for a few minutes at the start before joining the rest of the cast for the big action climax (although their scenes look like they were shot in a day or two). The same goes for Chuck Norris, who gets high billing despite being in the film for a grand total of three minutes, tops. At this point, any big name that joins the 'Expendables' franchise is understood to be a cameo and nothing more until the finished film can prove otherwise.

  • 7

    Steven Seagal in 'Executive Decision'

    In 1996, Steven Seagal was still near the height of his popularity, so it made perfect sense for Warner Bros. to sell 'Executive Decision' as a buddy-action film starring him and Kurt Russell. For a while, everything seemed normal enough. The film opens with the introduction of Seagal's tough-as-nails soldier and proceeds to set up a daring action scene where the continuously squinting hero leads a mid-air plane boarding to rescue hostages and retrieve a deadly chemical weapon. It's all mildly interesting and fairly familiar -- until Seagal's character is sucked out of the plane and dies a sudden and horrible death. To be fair, this is where 'Executive Decision' really makes you sit up and start paying attention ("Did they really just do that!?"), but it's a heartbreaking/baffling moment for Seagal fans. It was all stunt casting and misdirection, so you'd never see the character's death coming. To be fair, Seagal's face was removed from the cover of the home video release, leaving a very lonely Kurt Russell floating head, but every piece of marketing around the time of the film's theatrical release is as guilty as sin of selling Seagal as a main character and not a cameo.

    Warner Bros.
  • 8

    Danny DeVito in 'Mars Attacks!'

    In its attempt to recreate the star-packed disaster movies of the '70s, Tim Burton's 'Mars Attacks!' suffers from ensemble overload, with almost every speaking character played by someone you've seen before. No role inspires more head-scratching than Danny DeVito, whose character is so inconsequential that he doesn't even have a name. DeVito plays "Rude Gambler," who only has a scene or two before he's vaporized by the aliens. It's essentially a fun cameo, but it's strange that he's billed near the very top and gets premium real estate on the poster.

    Warner Bros.
  • 9

    Drew Barrymore in 'Scream'

    Of all the unexpectedly small roles, none are as effective or as iconic as Drew Barrymore in 'Scream.' Billed as a leading role alongside Neve Campbell, Barrymore only appears in the opening sequence, where she takes a menacing phone call and gets menaced by a masked killer before being brutally killed. Her death is shocking and unexpected, but the role is so much more than a mere cameo. The first 20 minutes of 'Scream' act as their own completely separate short film starring Drew Barrymore, and it's the single best thing in the entire franchise.

  • 10

    The Entire Cast of 'The Thin Red Line'

    When you watch Terrence Malick's 'The Thin Red Line,' you realize that Sean Penn actually got pretty lucky with his screen time in 'The Tree of Life.' Shot as a more traditional war movie and transformed into an art film in post-production, Malick excised entire performances from the film (including Gary Oldman, Bill Pullman, Mickey Rourke, Martin Sheen and Viggo Mortensen) and whittled others down to the bone. Adrien Brody, who had one of the main parts in the script, has only a few lines in the finished film. John Travolta has one scene. George Clooney shows up for a few seconds at the very end. John Cusack, John C. Reilly and Sean Penn show up in supporting roles that feel like they were once meatier. 'The Thin Red Line' is a great movie, but no film production has been more guilty of selling itself on star power that has almost no relevance in the finished film.