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.