A Will Smith movie packs in millions of people over Fourth of July weekend. No surprises there.

Yet Smith's "Hancock," the tale of an anti-social boozer who happens to be a superhero, comes with an abrupt plot twist, one that has divided critics and the moviegoing public in the real world (Critics and everyone else can't agree. Now there's a real surprise).

For those who have yet to see "Hancock," we won't give the secret away, but it has something to do with why Charlize Theron's soccer-mom-style character doesn't want Smith's surly superhero anywhere near her family.

Critics generally thought the turn the movie takes halfway through was a cheat, spoiling what had been a promising idea that was a fresh twist on the superhero genre in its own right.

The people who turned "Hancock" into an instant blockbuster beg to differ _ to the sum of $185 million worldwide at the box office in just a few days.

The plot twist in "Hancock" won't go down in cinema history alongside Darth Vader revealing he's Luke Skywalker's pappy in "The Empire Strikes Back" or Anthony Perkins turning out to be a slasher in his mom's housedress in "Psycho."

However, it does give us a chance to buzz once more about the really great curve balls _ and maybe a wild pitch or two _ that Hollywood has tossed our way.

Here's a look at some of the most memorable screen surprises, in no particular order:

MY GIRL: Has there ever been a stranger what-the-heck moment than the revelation that the enticing woman Stephen Rea lusts after in "The Crying Game" really is a guy? The dreamlike gotcha gesture delivered from beyond by Forest Whitaker's character was directed as much at male audiences everywhere who had to hit the reset button on their manhood after falling for Jaye Davidson as a hot new screen goddess only to learn he shared their XY chromosome makeup.

THE SECRET INGREDIENT IS US: How do you turn an utterly forgettable movie into one for the ages? Let Charlton Heston learn that the super-food of the future is made of humans so he can bellow "Soylent Green is PE-E-E-OPLE!" And don't forget the "Saturday Night Live" skit about a "Soylent Green" sequel where Phil Hartman impersonates Heston, learning that the powers that be didn't change the recipe like they promised, so he can holler "It's still PE-E-E-OPLE!"

HEAD IN THE SAND: Heston gets to curse out humanity in general in "Planet of the Apes" as he stumbles on the noggin of the Statue of Liberty lying on the beach and realizes he's been on Earth all along _ but in the distant future, after his species has blown itself up. Tim Burton's remake substitutes a terrible twist as astronaut Mark Wahlberg makes it off the simian world and returns to his planet, only to find a monkey named "Ape Lincoln" sitting on the Lincoln Memorial.

POOR BRUCE IS DEAD: With "Breakfast of Champions" and "The Story of Us," Bruce Willis' career might have been dead. But M. Night Shyamalan kept him alive by killing him off in the opening moments of "The Sixth Sense" but concealing that fact so completely that movie-goers were shocked into seeing the flick again and again after they learned he was a ghost. Audiences were somewhat less than shocked with Shyamalan and Willis' next surprise ending _ superheroes are real! _ in "Unbreakable."

READY FOR MY SHOWER, MR. HITCHCOCK: Perkins as his own mother has enduring shock value, but Alfred Hitchcock pulled a true stunner earlier in "Psycho" as the killer snuffed Janet Leigh, the movie's lead character up to that moment. That's like Dickens having Oliver Twist die of cholera in chapter three. Who do you root for when the heroine gets tossed in the trunk of her car and submerged in a swamp?

KEYSER SPACEY: As prime suspect Gabriel Byrne lay dying near the end of "The Usual Suspects," you just had to wonder "Well if it's not him, who the heck is Keyser Soze?" Watching Kevin Spacey transform from the grubby, gimpy little Verbal Kint into world-class criminal mastermind Soze in the space of one city block is one of those moments that makes you think "Yeah, this is why I like movies."

MY SISTER, MY MOM: Incest turns out to be the stuff of one of cinema's most artful surprises at the end of "Chinatown," when we learn that Faye Dunaway's little sister also is her daughter. And we get to see Jack Nicholson slap the information out of her _ repeatedly _ in a climax that's nothing short of a gut-punch.

MISSION IMPERTINENT: Speaking of slaps in the face, arguably the worst plot twist ever comes in Tom Cruise's first "Mission: Impossible" tale. Millions grew up watching Peter Graves' noble Jim Phelps run the Impossible Mission Force on the small screen. So when Jon Voight's Phelps turns out to be the bad guy in Cruise's version, it was disrespectful of both the source material and its fans. Why didn't Cruise just play Phelps himself, but as the hero everyone remembered the character for? Maybe Cruise was afraid that, like Graves, he would wind up hosting episodes of "Biography" in his golden years.