Monica Bellucci in Spectre: her name is on every poster, very early in the opening credits, and is featured prominently in much of the marketing, but she only appears on screen for a few minutes and her character basically exists solely so Bond has someone else to fuck.
Angelina Jolie was third billed in Sky Captain and the World of Tomorrow but was in it for about ten minutes. Laurence Olivier was also hyped as giving a performance from beyond the grave with CGI magic, but it amounted to basically one blurry scene of his face.
The all-time champ here is Eddie Murphy in Best Defense. Heavily hyped in the ads and 2nd billed after Dudley Moore. He wasn’t even in the original version of the film! They later filmed some scenes and added him into it. He never interacts with the main characters.
He did it for the paycheck and quickly regretted it. Terrible film.
When Ragtime was released, there was a lot of publicity about James Cagney appearing in the movie. Granted, Cagney was a movie legend and he hadn’t made a movie in twenty years. But he was only in a couple of scenes in the movie.
I haven’t seen Glengarry Glen Ross. But doesn’t Alec Baldwin’s character only appear in one scene? I know his character didn’t even exist in the original play. Despite this, Baldwin’s on the poster and clips of his performance were used to promote the movie.
True. http://www.avclub.com/article/why-iglengarry-glen-rossi-alec-baldwin-scene-is-so-82782
“Yet he arguably sets the tone for the entire movie, providing a much more concrete sense of the pressure these salesman are under.”
All the good ones that I know are taken, so I’ll post a more obscure one.
Vanishing Point. The film is billed as having Charlotte Rampling, but in the US version all her scenes were removed. So she’s one of two people on the packaging, but isn’t in the film at all!
All the Special Guest Stars on the series Police Squad! died violently before the opening credits even ran. 
Brando also got an Oscar nomination for about 10 or 15 minutes of screen time in A Dry White Season. Not sure where he was billed–I only saw the movie once back when i came out on cable.
How much screen time did Anthony Hopkins have in The Silence of the Lambs?
16 minutes – which always surprises me because you feel his presence throughout!
Darth Vader was onscreen for 12 minutes in *A New Hope. *
Just yesterday I saw “Infinitely Polar Bear,” a meh little film from about a year ago starring Mark Ruffalo and Zoe Saldana. I believe third-billed was Keir Dullea, who appears in one scene that’s maybe four minutes long, tops.
Cool to see him, though – looking quite a bit like he did when he was “aged” with makeup for that one scene back in 1968!
And the actor isn’t top-billed, or second-billed, or third- or fourth- or fifth-billed; the end credits I just viewed don’t list him sixth or seventh or eighth, either.
Sean Connery was not credited for the 1991 Robin Hood , he was only in 1 scene. But he got $250k which he gave to charity.
He also played Robin Hood in a 1976 movie where he got top billing.
Jack Nicholson was second-billed in A Few Good Men but only appeared in four scenes.
That would be Sizzle Beach, U.S.A. (aka Malibu Hot Summer)
Along similar lines: the indie film * Motorama* features Drew Barrymore in a very brief, 30-second dream sequence. Even though she wasn’t highly billed, the DVD cover prominently features her face with the tagline: “There’s only one way to win the girl of your dreams” …which has nothing to do with the movie’s plot!!
Sidekicks had Chuck Norris prominently billed, but he appeared in a cameo at the end and in some short dream sequences.
But, of course, Chuck Norris can star in a film without even appearing in it.
Anna Paquin got stupid high billing for Days of Future Past with something like 10 seconds of screen time and also no lines. THAT has to be the record.
(I understand there’s an alternate cut that they later put on DVD with her actually in the movie, but that’s irrelevant to the discussion, IMO. As originally seen in theaters and video release, she’s simply a background prop.)
Bryan Cranston had an unfortunately small amount of screen time in the recent Godzilla, particularly considering how front-and-center he was for all the marketing.
Michael O’Donoghue’s execrable Mr. Mike’s Mondo Video was advertised with a star-studded cast, including Carrie Fisher, Teri Garr, Margot Kidder, Debbie Harry, and several SNL stars including Bill Murray. Nearly all of these actors were onscreen for, at most, a few seconds.