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 .