Terminator Salvation (2009)
The Cameo: We witness the arrival of the original T-800. Aptly for a cyborg, Schwarzenegger's youthful face was digitally inserted.
If The Character Had More Screen Time: The franchise could really go full circle by following Arnie back to 1984 and the start of The Terminator .
Wayne's World (1992)
The Cameo: Wayne (Mike Myers) is pulled over by a traffic cop, only to realise it's the T-1000 (Robert Patrick) from Terminator 2: Judgement Day .
If The Character Had More Screen Time: It'd be because Skynet had just found out that it's not John Connor who saves the future Earth, it's Garth (Dana Carvey).
24 Hour Party People (2002)
The Cameo: When unreliable narrator Tony Wilson (Steve Coogan) catches Magazine singer Howard Devoto (Martin Hancock) shagging his wife, the real-life Devoto turns up to declare that "I definitely don't remember this happening."
If The Character Had More Screen Time: Hmm… Joy Division? Sure. Happy Mondays? Absolutely. But Magazine? Hardly the stuff of indie music legend.
The Cameo: The best of Quentin Tarantino's many cameos is a suitably wordy (and completely tangential) affair, as he tells a filthy joke before getting gunned down in a shootout.
If The Character Had More Screen Time: The, shall we say, limitations of QT's acting ability would become even more apparent.
Fantastic Mr Fox (2009)
The Cameo: Jarvis Cocker already had a Harry Potter cameo under his belt, but went one better by being turned into stop-motion as banjo-twanging farmer Petey.
If The Character Had More Screen Time: He'd eventually start chronicling the sex lives of Mr and Mrs Fox and all of their animal friends.
Indiana Jones And The Temple Of Doom (1984)
The Cameo: The airport scene at the end of the film's Shanghai sequence is a proper jolly boys' outing, featuring Steven Spielberg and George Lucas as extras, plus Dan Aykroyd as the guy who books Indy onto the worst possible flight out of town.
If The Character Had More Screen Time: To be honest, we're still surprised Aykroyd doesn't rock up in India later in the film.
High Fidelity (2000)
The Cameo: A film about one-upmanship in music taste stands and falls on the quality of its references, and the biggest coup is having The Boss himself, Bruce Springsteen, turn up as mentor to John Cusack's Rob Gordon.
If The Character Had More Screen Time: He'd suffer a backlash at the hands of Rob's snobby record store employee Barry (Jack Black).
The League Of Gentlemen's Apocalypse (2005)
The Cameo: Famously, the fourth member of the League, Jeremy Dyson, never appears on screen. So in a wry in-joke, they kill off 'Dyson' (played by Michael Sheen) before the opening credits.
If The Character Had More Screen Time: The film is already way too meta. Any more actor/character confusion and our heads would probably explode.
Once Upon A Time In The West (1968)
The Cameos: The looong opening sees the great Western character actors Woody Strode and Jack Elam (plus Leone regular Al Mulock) play three gunslingers waiting for - and then gunned down by - Charles Bronson's drifter. But it might have been even better - Leone originally intended for it to be Eastwood, Wallach and Van Cleef.
If The Characters Had More Screen Time: That opening sequence would be even loooonger.
Spider-man 3 (2007)
The Cameo: Sam Raimi cast his old Evil Dead mucker Bruce Campbell in all three Spider-man movies as, respectively, a ring announcer, a snooty usher, and the piece de resistance, this preening, pretentious maitre d'.
If The Character Had More Screen Time: Maybe it's the same character - a secret superhero quietly stalking Peter Parker across the films.
Out Of Sight (1998)
The Cameo: Steven Soderbergh joined the dots between two Elmore Leonard adaps by getting Michael Keaton to reprise his role as Ray Nicolette, first played in Tarantino's Jackie Brown .
If The Character Had More Screen Time: It'd be fun watching screen Batmans Clooney and Keaton face off as love rivals for J. Lo's attentions.
The Blues Brothers (1980)
The Cameo: In a film composed of loving tributes to R&B legends, the greatest is surely Ray Charles' appearance - firing a warning shot at the kid trying to rub him, before joining Jake and Elwood in a rendition of 'Shake A Tail Feather.'
If The Character Had More Screen Time: It's hard to escape the conclusion that he'd somehow end up in the climactic car chase, navigating through hearing alone.
The Darjeeling Limited (2007)
The Cameo: Wes Anderson nods to companion short Hotel Chevalier by including Natalie Portman's character in his end-of-film montage... but her appearance is completely baffling if you've only watch the main feature.
If The Character Had More Screen Time: More romantic tensions with Jason Schwartzman, as per Hotel Chevalier .
The Cameo: Average Joe's has forfeited the Dodgeball final - but wait! The judges can overturn the decision, and the casting vote lies with none other than Chuck Norris.
If The Character Had More Screen Time: He'd join the match, setting up the bloodiest game of Dodgeball in history.
The Cameo: No wonder card-sharp Maverick (Mel Gibson) looks confused. The bank robber holding him up looks exactly like Gibson's old Lethal Weapon partner, Danny Glover.
If The Character Had More Screen Time: Riggs and Murtaugh, the cowboy years.
Being John Malkovich (1999)
The Cameo: OK, so we've accepted that, on the seventh-and-a-half floor at LesterCorp, there's a portal that gives access to the inside of John Malkovich's mind. So why is it so hard to believe that Malkovich's best mate is Charlie Sheen?
If The Character Had More Screen Time: It would be revealed that the portal business was part of the tiger-blood drinking Charlie's strategy for "winning."
Silent Movie (1976)
The Cameo: Long before The Artist , Mel Brooks' pastiche of pre-talkie cinema broke the silence only for the world's most famous mime, Marcel Marceau, to deliver the film's only line: "Non!"
If The Character Had More Screen Time: It would have been nice to have a genuine practitioner of mime to star in a film on the subject.
Iron Man (2008)
The Cameo: The worst kept secret in superhero movies, although it's still an undeniable wow moment as Samuel L. Jackson's Nick Fury attempts to enlist Tony Stark (Robert Downey, Jr) into The Avengers .
If The Character Had More Screen Time: Sadly, the increased Fury of Avengers -advertising was partly to blame for the disappointment of Iron Man 2 .
Young Frankenstein (1974)
The Cameo: Great cameos often require a double-take, nowhere more so than in the realisation that the blind, bearded hermit whose clumsiness increasingly frustrates the Monster is none other than Gene Hackman.
If The Character Had More Screen Time: He'd get to share a scene with fellow Gene (and Bonnie And Clyde co-star) Wilder.
Robin Hood: Prince Of Thieves (1991)
The Cameo: Richard the Lionheart is back from the Crusades to attend Robin and Marian's wedding - and in a quadruple in-joke, the King Of England is played by Sean Connery: an ex-Robin, Kevin Costner's fellow Untouchable , a man who'd not long filmed The Last Crusade , and very, very Scottish.
If The Character Had More Screen Time: Connery would have sorted out Alan Rickman in a heartbeat, leaving Costner with little to do but wash his mullet.
Invasion Of The Body Snatchers (1978)
The Cameos: Philip Kaufman's remake of the 1956 classic was one of the first movies to include kisses to the past with cameos by original director Don Siegel and star Kevin McCarthy, who reprises his most iconic line: "They're here!"
If The Character Had More Screen Time: McCarthy would join forces with the 1978 hero (Donald Sutherland) and maybe even bring about a happier ending.
The Cameo: Long before the ubiquity of his walk-ons in Marvel superhero movies, Stan Lee had already been given his best tribute, playing mentor to comic-book geek Brodie (Jason Lee).
If The Character Had More Screen Time: Stan's the man...and he fits right into Kevin Smith's View Askewniverse. We'd like to have seen him take a job at the Quick Stop.
The Muppet Movie (1979)
The Cameo: How to raise the bar when your TV show has already featured numerous Hollywood legends (and Bruce Forsyth) as guests? How about casting Orson Welles as imperious studio boss Lew Lord?
If The Character Had More Screen Time: Welles would help Kermit to find Rosebud, the long-lost symbol of his innocence. Note: Rosebud, in this case, actually is a flower. Kermit is a frog, after all.
Shaun Of The Dead (2004)
The Cameos: Shaun (Simon Pegg) and co bump into a other posse of survivors led by Yvonne (Pegg's ex- Spaced flatmate Jessica Stevenson) and including Martin Freeman, Tamsin Greig and Matt Lucas.
If The Characters Had More Screen Time: Aside from the heroine's gender, Yvonne Of The Dead wouldn't be radically different to what ended up on screen.
Pirates Of The Caribbean: At World's End (2007)
The Cameo: Inevitable from the moment Johnny Depp revealed he'd based Captain Jack Sparrow on Keith Richards. Still, fair play to Keef for being such a sport as Sparrow, Snr.
If The Character Had More Screen Time: Richards' couldn't be any more self-indulgent than the rest of this dreary film. He livens things up considerably when he shows up.
The Cameo: Zoolander (Ben Stiller) and Hansel (Owen Wilson) compete in a walk-off. The judge? The master of glacial poise and flamboyant cheekbones, David Bowie.
If The Character Had More Screen Time: The temptation to have Bowie unmasked as the Goblin King would be too strong to ignore.
Toy Story 3 (2010)
The Cameo: Nestling amongst the toys in Bonnie's bedroom is a cuddly forest sprite instantly familiar to fans of Studio Ghibli. It's none other than Totoro.
If The Character Had More Screen Time: He'd be the outside man assisting the breakout of Andy's toys from Sunnyside, and he'd bring along the Catbus as a getaway vehicle.
It's A Mad, Mad, Mad, Mad World (1963)
The Cameo: The cheekiest moment in Stanley Kramer's cameo-packed madcap comedy is to have slapstick legends the Three Stooges simply standing in the frame, doing nothing.
If The Characters Had More Screen Time: They'd soon revert to type, and steal the thunder from their fellow stars.
The Player (1992)
The Cameo: It's easier to list who doesn't have a cameo in Altman's Hollywood satire, but the best go to Bruce Willis and Julia Roberts, roped in to provide the studio-sanctioned happy ending in film-within-a-film Habeas Corpus .
If The Characters Had More Screen Time: We'd be watching Habeas Corpus .
Wayne's World 2 (1993)
The Cameo: "I know it's a small part, but I think we can do better than this," says Wayne (Mike Myers). Cue a quick switcheroo, and Charlton Heston wheeled in to add some class.
If The Character Had More Screen Time: He'd find his true love from Gordon Street; Wayne and Garth would be his best men. The stag do would be awesome.
Taxi Driver (1976)
The Cameo: Travis Bickle (Robert De Niro) picks up a passenger with murder on his mind, played by the film's director Martin Scorsese.
If The Character Had More Screen Time: Scorsese actually appears twice in the film; any more screen time and it would lend credence to the theory his character is the Devil, tempting Bickle into his own bloody catharsis.
Sunset Boulevard (1950)
The Cameo: Billy Wilder's sour satire about Hollywood has-beens strikes its bitterest blow by showing washed-up Buster Keaton involved in a gloomy game of poker.
If The Character Had More Screen Time: Wilder would realise that comedic talent like Keaton's never dies, and let him loose on the film.
The Wedding Singer (1998)
The Cameo: By the late 1990s, mainstream Hollywood was cottoning to the fact that Steve Buscemi had become a badge of indie cool and authenticity. Ergo his show-stopping performance as a drunk, bitter best man.
If The Character Had More Screen Time: Not making a Dave Veltri spin-off was one of 1990s' great lost opportunities. Still, it's not as if Buscemi has been out of work since.
Monty Python's Life Of Brian (1979)
The Cameo: Serendipity, as the Monty Python boys found out their hero Spike Milligan was on holiday close to the filming location. In a suitably back-handed compliment, they cast him as a prophet abandoned by his disciples in favour of Brian.
If The Character Had More Screen Time: Presumably, they'd have had to reimburse Milligan for ruining his holiday.
The Cameo: Cameo king Matt Damon ( Finding Forrester , Che , Team America ) has his greatest mini-moment as Donny, the college singer who pens anthem "Scotty Doesn't Know" about his greatest sexual conquest.
If The Character Had More Screen Time: He'd follow the Eurotrippers on their Continental adventure, providing a running commentary on the film's events via song.
The Hangover (2009)
The Cameo: Where the hell did that tiger come from? Well, the drunken Wolf Pack nicked it from Mike Tyson's pad, and he ain't best pleased.
If The Character Had More Screen Time: He'd have ended up in The Hangover Part 2 as well, sparing everyone that awkward retracted invitation for Mel Gibson.
Hot Fuzz (2007)
The Cameo: In any other film, the sight of Peter Jackson as a criminal Santa would be the cameo highpoint. But Edgar Wright outdid himself by the incongruous casting of Cate Blanchett as Simon Pegg's ex-girlfriend, face obscured under a surgical mask.
If The Character Had More Screen Time: She'd reappear in the film's final act, helping Nicholas Angel and Danny Butterman as a surgical ninja.
Coming To America (1988)
The Cameo: John Landis nods to a past classic when Prince Akeem (Eddie Murphy) tosses money to two homeless men, revealed to be Trading Places ' villains the Duke brothers (Don Ameche and Ralph Bellamy).
If The Characters Had More Screen Time: "We're back!" exclaim the greedy gents - and wouldn't it be fun to see them get back to the top?
The Cameo: "Oh no, not again!" In space, everybody can see an alien burst out of John Hurt's stomach. Although not all of them then proceed to sing and dance on the table in a straw hat.
If The Character Had More Screen Time: Imagine what Mel Brooks might have made of the facehugger scene.
Austin Powers in Goldmember (2002)
The Cameos: Arguably the most high-profile cameo team of the last decade, as Steven Spielberg directs Tom Cruise, Gwyneth Paltrow, Kevin Spacey and Danny DeVito as the stars of Austinpussy .
If The Characters Had More Screen Time: The result would undoubtedly be better than Goldmember .
The Birds (1963)
The Cameo: It's hard to pick just one of Hitchcock's many fleeting appearances, but it's this one that has become his most iconic - by virtue of sharing the screen with a pair of small dogs.
If The Character Had More Screen Time: Hitch would play an animal expert called in to solve the birdemic... But who inevitably gets pecked to death.
X-Men: First Class (2011)
The Cameo: Having long established that Wolverine doesn't age, this 1960s-set prequel has fun having Hugh Jackman tell the young Professor X and Magneto where to shove their plans.
If The Character Had More Screen Time: A major continuity headache, given that he doesn't join Professor X's lot for several decades.
Hot Shots! Part Deux (1993)
The Cameo: As Topper Harley (Charlie Sheen) heads upriver, he passes Captain Willard (Martin Sheen) heading the other way - a cute in-joke considering father & son's shared 'Nam heritage in Platoon and Apocalypse Now . Cementing the joke: "I loved you in Wall Street !"
If The Character Had More Screen Time: It wouldn't be beyond the realms of Hot Shots ' implausibility for Sheen, Snr to tag along with Charlie for the rest of the film.
Annie Hall (1977)
The Cameo: The medium is the message, so when Woody Allen can no longer cope with a clueless academic, who better to do the take-down than postmodern guru Marshall McLuhan? The highbrow version of getting pwned.
If The Character Had More Screen Time: Eventually, McLuhan would start deconstructing Allen's own comedy and Woody would be reduced to a gibbering wreck.
Pulp Fiction (1994)
The Cameo: Christopher Walken gets 'The Gold Watch' off to a gripping start simply by reciting a monologue of wartime imprisonment and anal discomfort in his trademark stilted delivery.
If The Character Had More Screen Time: He'd still be hanging around as Butch's (Bruce Willis) guardian angel, coming to the rescue in the gimp's cellar.
The Cameo: "Do you like scary movies?" Unexpectedly killing off your most famous actress isn't exactly a new gimmick, but Drew Barrymore's bite-sized appearance distils things down to a cameo-length scare.
If The Character Had More Screen Time: You may as well drop the slasher element entirely and make a high school comedy.
The Cameo: Survivors of the zombie apocalypse hole up in a Hollywood mansion, only to find that the owner - Bill Murray - has disguised himself as the undead in order to continue playing golf.
If The Character Had More Screen Time: We'd be robbed of one of the freakiest meta-jokes in cinema, as Murray is mistaken for a zombie and shot. His deathbed confession: he regrets doing Garfield .
The Cameos: Ron Burgundy's crew face off in a violent confrontation against rival news anchors - including Vince Vaughn, Luke Wilson, Ben Stiller and, improbably, Tim Robbins.
If The Characters Had More Screen Time: It'd become an epic tale of the San Diego television industry. Think Mad Men , with trident murders.
Tropic Thunder (2008)
The Cameo: Tom Cruise's appearance as overweight, balding, bad-dancing studio exec Les Grossman was so shrouded in secrecy that Internet sites publishing leaked photos were handed 'cease or desist' orders.
If The Character Had More Screen Time: It'd quickly get wearying if Cruise had to be that OTT for a whole film. That said, there's scope for him to crop up in other films about Hollywood.
Glengarry Glen Ross (1992)
The Cameo: Not everyone could upstage Pacino, Lemmon and Spacey, but Alec Baldwin knocks it out of the park playing a character specially created by David Mamet for the film version of his play. Remember - Always. Be. Closing.
If The Character Had More Screen Time: The intensity would be as exhausting for Baldwin as it would be for us. Better by far to leave Baldwin with the honour of cinema's greatest cameo.