The Sequel Character: While Godzilla had faced-off against many worthy opponents, notably Mothra, it wasn't until Ghidorah, The Three-Headed Monster (1964) that the reptile met his biggest nightmare: a three-headed dragon.
If They'd Been In The Original: It would have been obvious from the start that Godzilla had humanity's best interests at heart, because - compared to Ghidorah - he's a hero.
The Sequel Character: Scottish survivor of the events of 28 Days Later , played by Robert Carlyle, who underlines the bleakness of humanity's plight when he has to abandon his wife to the rage-filled hordes.
If They'd Been In The Original: Possibly, we'd have more investment in his terrible dilemma… but making him a completely new character helps to sell the idea that the whole country (rather than a few characters) is in turmoil.
The Sequel Character: Lunar base commander played by William Shatner in Airplane II: The Sequel (1982), who has to bury his differences with Ted Stryker to help land a damaged space shuttle but is more worried about all of the flashing, blinking lights in his base.
If They'd Been In The Original: The joke wouldn't have worked. Robert Stack played the equivalent character first time around because of his background in 1950s war movies; Shatner has been cast in the sci-fi sequel precisely because he is James T. Kirk.
Bernie And Roz Focker
The Sequel Characters: So, how did Gaylord Focker get the way he is? We soon find out when we Meet The Fockers (2004), and are introduced to Dustin Hoffman and Barbara Streisand's hippie-ish, sexually liberated folks.
If They'd Been In The Original: We dread to think.
Todd and Stuart
The Sequel Characters: Bored American businessmen who join Elite Hunting in Hostel: Part II (2007) in order to torture a group of kidnapped holidaymakers.
If They'd Been In The Original: It is doubtful they would have had much to do. By saving them for the sequel, Eli Roth expanded his storyworld by giving an insight into why these sadists would be interested in Elite Hunting.
The Sequel Character: Think that Ocean's Eleven was too much of a lads' affair? Catherine Zeta Jones redressed the balance in Ocean's Twelve (2004) as the Europol agent who has a complicated history with Rusty Ryan.
If They'd Been In The Original: Either they'd have to switch the action from Vegas to Monte Carlo, or else stretch the definition of 'Europol.'
The Sequel Character: It's a tough gig for anyone trying to recapture memories of Dorothy's friends in Return To Oz (1985), but this tubby, military-minded wind-up robot came close.
If They'd Been In The Original: He'd be the Tin Man's bitch.
The Sequel Character: How do you take down the greatest predator that ever lived? By hiring the second greatest predator, as Pete Postlethwaite's big game hunter rises to a new challenge attempting to capture a T-Rex in The Lost World: Jurassic Park (1997).
If They'd Been In The Original: Either Tembo would have had uncanny knowledge that the dinosaurs were going to break loose, or else he'd be hunting them in their enclosures, which hardly seems sporting.
The Sequel Character: Whistleblowing accountant played by Joe Pesci, whom Riggs and Murtaugh are asked to protect in Lethal Weapon 2 (1989) and who later becomes part of the franchise's furniture.
If They'd Been In The Original: Ironically, it would make Lethal Weapon much closer in tone to the increasingly cosy sequels than the tough original.
The Sequel Character: Tyrannical ruler of Sunnyside Daycare in Toy Story 3 (2010). He might smell of strawberries, but the aftertaste is bitter - abandoned by his owner, Lotso symbolises the dark side of the toy/child partnership.
If They'd Been In The Original: Woody would have got wise to how important it is to be loved, effectively ruining the drama of his dilemma in Toy Story 2 .
The Sequel Character: Ectoplasmic entity with the voice of Seth MacFarlane and a metaphorical rod up his arse - the worst imaginable boss for a sarcastic demon during Hellboy 2: The Golden Army (2008).
If They'd Been In The Original: How do you know he wasn't?
The Sequel Character: While the Pirates Of The Caribbean sequels never matched the first part's swagger, Billy Nighy's octopoid pirate - first seen in Dead Man's Chest (2006) - remains a benchmark in the synthesis of actor and CGI.
If They'd Been In The Original: As we would learn from the bloated sequels, too many characters aboard and the ship is liable to sink.
The Sequel Character: Old-school roadie played by Ralph Brown, who helps Wayne and Garth to set up Waynestock in Wayne's World 2 (1993) while providing dubious anecdotes about robbing sweet shops guarded by Bengal tigers.
If They'd Been In The Original: The jokes would be much the same, although with the central premise of a music festival it's difficult to see why Del would be hanging around.
The Sequel Character: The 'annoying kid sidekick' got a new, non-annoying lease of life with Indiana Jones' Chinese friend, played by 80s child acting icon Ke Huy Quan in Indiana Jones And The Temple Of Doom (1984).
If They'd Been In The Original: Given that Temple is actually a prequel, Short Round should've been in Raiders Of The Lost Ark . What happened to him, Indy?
The Sequel Character: Burt Kwouk first played Inspector Clouseau's manservant in A Shot In The Dark (1964), and continued to plague his boss with surprise attacks for the rest of the Peter Sellers' Pink Panther films.
If They'd Been In The Original: Since Clouseau is off on a job during The Pink Panther , that would mean that he was in the habit of taking Cato with him. Imagine the bills for damage to hotel rooms!
The Sequel Character: Simon Pegg's IMF boffin was a mere cameo in Mission: Impossible 3 (2006) but he was reluctantly called into field duty for Ghost Protocol .
If They'd Been In The Original: It would've shown amazing foresight on the part of Brian DePalma, given that Pegg only secured his first major role (in ITV sitcom Faith In The Future ) in 1996.
The Sequel Character: Mob boss (played by renowned acting coach Lee Strasberg) whose dual obsessions - opening a casino in Cuba, and taking vengeance on Michael Corleone - provide the narrative motor of The Godfather Part 2 (1974).
If They'd Been In The Original: It would have added further texture to an already rich saga, given that Roth was on friendly terms with Michael's father, Vito, before Michael had Roth's associate Moe Greene killed.
The Sequel Character: One of the joys of the X-Men series is its strength in depth. Think Bryan Singer had introduced all of the greats in the first film? Five minutes into X2 (2003), as Nightcrawler teleports his way into and through the White House, it was obvious he still had great characters up his sleeve.
If They'd Been In The Original: Actually, Nightcrawler would have come in handy during the first film's climactic scrap atop the Statue of Liberty. Oh well.
The Sequel Character: Harlem shop owner who gets roped into helping John McClane do what "Simon says" in Die Hard With A Vengeance (1995), transforming a 'lone wolf' franchise into more of a buddy-buddy thing.
If They'd Been In The Original: Tricky, given Die Hard is set on the opposite side of America, yet in a parallel universe it's possible to imagine a pre-fame Samuel L. Jackson in Reginald VelJohnson's proto-buddy role as Al Powell.
The Gyro Captain
The Sequel Character: Rival-turned-ally of Max Rockatansky in Mad Max 2 (1981), who has solved the problem of getting around in the post-apocalypse by flying a gyrocopter. Bruce Spence also played Jedediah - a variant of the same character - in Mad Max Beyond Thunderdome .
If They'd Been In The Original: Spence's eccentric performance is perfect for the more fantastical sequels but it's hard to imagine him fitting in to the raw, brutal original.
The Sequel Character: Tom Cruise's cocky pool player in The Color Of Money (1986), whose wayward talent becomes the focus of one-time hustler Fast Eddie Felson's redemption.
If They'd Been In The Original: The Hustler was made in 1961. Tom Cruise was born in 1962. You do the sums.
The Sequel Character: Proof that there is no end to the existential richness of toys, Toy Story 3 (2010) delivered one of the saga's best gags in revealing the conflicted impulses of a would-be man's man brought up as a girl's plaything, wittily voiced by Michael Keaton.
If They'd Been In The Original: The late additions to the gang are so likeable that it's a shame Ken isn't in all three films.
The Sequel Character: Nuclear scientist played by Alfred Molina in Spider-man 2 (2004), whose experiments with robotic arms transform him into Doctor Octopus - a worthy opponent for Peter Parker.
If They'd Been In The Original: The mix would have been spoiled by too many supervillains. A lesson unheeded by Spider-man 3 , of course.
The Sequel Character: The object of Antoine Doinel's affections in Stolen Kisses (1968) played by Claude Jade, who becomes his wife, then his ex-wife, in subsequent movies in Francois Truffaut's semi-autobiographical series.
If They'd Been In The Original: Doinel is a punk teenager in borstal during The 400 Blows . There's no room for romance there.
The Sequel Character: A tough call between Lang and Ivan Drago as Rocky Balboa's greatest sequel opponent, but the Rocky 3 (1982) character get the nod because a) he actually beats Rocky and b) he's only Mr bloody T.
If They'd Been In The Original: Lang would only get in the way of the rich four-film arc involving Apollo Creed.
The Sequel Character: 19th century science teacher played by Mary Steenburgen, who complicates the timelines in Back To The Future Part 3 (1990) when a) Doc Brown changes history by rescuing her and b) they fall in love.
If They'd Been In The Original: It's just about possible, but assuming that Clayton was the same age in 1885 as Steenburgen was when she made the film (36), she would be 106 years old in 1955.
The Sequel Character: Zombie played by Sherman Howard in Day Of The Dead (1985), who is subjected to scientist tests - including reading Stephen King novels! - to see if his humanity can be restored. It can, sort of: he certainly remembers vengeance.
If They'd Been In The Original: No way would the farmhouse prisoners of Night Of The Living Dead would have survived until dawn.
The Sequel Character: One-eighth size clone of Dr Evil, played by Verne Troyer. The character was introduced in Austin Powers: The Spy Who Shagged Me (1999) and instantly become part of the series' iconography.
If They'd Been In The Original: If anything, Austin Powers: International Man Of Mystery nowadays feels lacking, precisely because Mini-Me isn't in it.
The Sequel Character: It's bad enough that New York falls victim to Gremlins 2: The New Batch (1990), but now they have to deal with a super-intelligent Gremlin (voiced by Tony Randall) who has drunk a brain serum and developed a taste for Sinatra.
If They'd Been In The Original: Kingston Falls would have stood no chance.
The Sequel Character: "What a lovely, lovely voice!" Or not. Tom Hardy rasps his way to threequel-stealing glory as the brute what breaks Batman's back in The Dark Knight Rises (2012).
If They'd Been In The Original: Given his past allegiance to the League of Shadows, it's not impossible he might've been moping around in Bhutan during the events of Batman Begins .
The Sequel Character: The stand-out newcomer in Aliens (1986), Bill Paxton's jittery Space Marine symbolises both humanity's powerlessness in the face of the xenomorphs, but also, ultimately, his decency and fighting spirit. Not to be confused with Hicks.
If They'd Been In The Original: The crew of the Nostromo would have benefitted from greater firepower, but Hudson probably would've panicked before making any real difference.
Jabba The Hutt
The Sequel Character: Younger viewers should probably look away now, but for Star Wars fans of a certain vintage, Tatooine's ugliest gangster wasn't introduced to audiences in an awkward overlay of computer FX over the unused humanoid form, but as a full-throated animatronic nightmare in Return Of The Jedi (1983).
If They'd Been In The Original: As younger viewers will be able to tell you, he's just another awkwardly CG'd creature in a "Special" edition full of 'em.
The Sequel Character: Herbert Lom's character in the Pink Panther series is Commissioner of the Parisian police when introduced in A Shot In The Dark (1964), then Chief Inspector, then a deranged lunatic as he is gradually driven mad by the incompetence of Inspector Clouseau.
If They'd Been In The Original: Dreyfus' mental decline would have been a lot steeper and swifter.
Puss In Boots
The Sequel Character: Feline assassin-turned-compadre of Shrek and Donkey. A mainstay since Shrek 2 (2004), Antonio Banderas' character even got his own spin-off.
If They'd Been In The Original: Banderas' comic double-act with Eddie Murphy would have muscled Mike Myers out of the action, robbing the franchise of the sweetness of its central bromance.
Khan Noonien Singh
The Sequel Character: You might argue that, since genetically supercharged villain Khan first appeared in TV ep Space Seed , his presence in Star Trek 2: The Wrath Of Khan (1982) shouldn't qualify for this list. But there can be no such objections to including his alt.universe equivalent in Star Trek Into Darkness (2013).
If They'd Been In The Original: While Khan would given some much needed motion to Star Trek: The Motion Picture , that would have been a mistake. Clearly, he's the go-to guy for raising the stakes second time around.
The Sequel Character: How to inject new life into an ailing franchise? Just add Rock. Dwayne Johnson's agent provided a fitting foil for Vin Diesel in Fast Five (2011) and has now become part of the gang.
If They'd Been In The Original: We might now be looking at the greatest action franchise of all time, instead of the guiltiest pleasure of recent times.
The Sequel Character: An obvious one, but easy to miss. JC is but a foetus by the end of The Terminator , meaning that it isn't until Terminator 2: Judgement Day (1991) that we get to see what all of the fuss is regarding Edward Furlong's saviour-to-be.
If They'd Been In The Original: It could only be in a flashforward to a grizzled, Christian Bale-type in the future.
The Sequel Character: Android officer aboard the Sulaco in Aliens (1986), who android-hating Ripley learns to love because, beneath the frosty exterior, really Bishop is a sweetie.
If They'd Been In The Original: Alien would have been robbed of one of its best twists in malign android Ash. That said, it would have made sense to cast Lance Henriksen given the later retconning that Bishop was based on the likeness of company boss Charles Bishop Weyland.
The Sequel Character: Take your pick - Michelle Pfeiffer in Batman Returns (1992) or Anne Hathaway in The Dark Knight Rises (2012). Either way, it's slinky catsuits and feline intuition for the win.
If They'd Been In The Original: As Bruce Wayne's female mirror image, it's important to establish the ground rules of Gotham life before introducing Catwoman - not least because she's so sexy she'd distract from the storytelling.
The Sequel Character: The Good, The Bad And The Ugly (1966) is technically a prequel to Sergio Leone's earlier Westerns, but there's no doubt that Eli Wallach's foul-mouthed bandit - aka the Ugly - completes the set in terms of Leone's characters.
If They'd Been In The Original: Inevitably, he would have got in the way and made a right mess of Clint Eastwood's plans in A Fistful Of Dollars .
The Sequel Character: A rootin' tootin' cowgal and fictional pal of Sheriff Woody on TV, whose toy equivalent (voiced by Joan Cusack) becomes the heart of the entire trilogy in Toy Story 2 (1999) when she reveals the heartache of abandonment.
If They'd Been In The Original: The only place the character could possibly have worked would have been as a prisoner in Sid's house… which would mean she'd have been mutilated and experimented upon. Not a great start for the character.
The Sequel Character: J.K. Rowling certainly knew how to maintain the momentum over seven stories (and eight films), meaning that Gary Oldman's pivotal character - perceived as an enemy until he's revealed as his godson's most loyal protector - isn't introduced until Harry Potter And The Prisoner Of Azkaban (2004).
If They'd Been In The Original: A fleeting mention might have been OK, but given how many characters already had to be introduced in The Philosopher's Stone , Sirius would have been lost in the mix.
The Sequel Character: Think Arnold Schwarzenegger's Terminator was formidable? You ain't seen nothing. Robert Patrick's upgrade, made from shape-shifting liquid metal, gives Arnie an opponent worth fighting in Terminator 2: Judgement Day (1991).
If They'd Been In The Original: James Cameron would have fumbled the pre-CGI attempts at the FX, killing off his promising career in its prime.
The Sequel Character: It's easy to miss that The Silence Of The Lambs (1991) is a follow-up to Manhunter , partly because the recurring roles of Hannibal Lecter and Jack Crawford were recast, but mainly because Oscar-winning Jodie Foster makes the film about her.
If They'd Been In The Original: Major rewrites would have been necessary. Even when Manhunter was remade as Red Dragon to complete the Anthony Hopkins trilogy, nobody thought of sticking Clarice into the story.
The Sequel Character: Although technically introduced in the Star Wars Holiday Special (but let's never speak of it again), this cool-as-fuck bounty hunter made his film debut as the captor of Han Solo in The Empire Strikes Back (1980) to become a fanboy favourite.
If They'd Been In The Original: You be can sure George Lucas regrets that he wasn't, given the pains he took to destroy the character's mystique by revealing his clone-child origins in the prequels.
The Sequel Character: Yes, pedants, he appears in The Fellowship Of The Ring , albeit as a pair of glowing eyes in the darkness. Yet the arrival proper of Andy Serkis' mo-capped marvel in The Lord Of The Rings: The Two Towers (2002) brought the series' most complex and memorable creation, and a landmark in movie FX.
If They'd Been In The Original: We'd hope he'd have more to do than be merely a pair of glowing eyes in the darkness.
Professor Henry Jones
The Sequel Character: Indiana Jones' pa is fussy and professorial... yet, as played with a twinkle in his eye by Sean Connery in Indiana Jones And The Last Crusade (1989), he's also one of cinema's coolest dads.
If They'd Been In The Original: It wouldn't have been fair to upstage Harrison Ford on his first gig as Indy. Half the fun of Last Crusade is seeing one of cinema's most confident actor/character combos being thoroughly upstaged by Connery.
Ernst Stavro Blofeld
The Sequel Character: We could fill this list with characters from James Bond films, so we'll settle for just one. From Russia With Love (1963) is not only a direct sequel to Dr No , it's also the film where Ernst Stavro Blofeld (and his cat) took charge of bringing down 007.
If They'd Been In The Original: There would be little appreciable difference, as he would only appear behind a desk, face unseen, giving his orders to Dr No.
The Sequel Character: Heath Ledger's outwardly/inwardly scarred Joker made such an immediate impression in The Dark Knight (2008) - genuinely, unsettlingly unpredictable - that last year's trilogy-closer The Dark Knight Rises arguably suffered from the late actor's absence.
If They'd Been In The Original: The character is foreshadowed in the closing scenes of Batman Begins ; had we actually seen Ledger, the Internet would have been ablaze with anticipation for years.
The Sequel Character: With sequels, great characters come. And none greater, surely, than the Frank Oz voiced Muppet grandmaster who gives Luke the tools to defeat Darth Vader in The Empire Strikes Back (1980). Iconic, likeable and forever punching above his weight.
If They'd Been In The Original: Ignore the Yoda-heavy prequels. There's a very good reason Yoda isn't in A New Hope : Luke's discovery that he's been speaking to Yoda all this time is (or, WAS) one of Star Wars ' greatest surprises.