Predator 2 (1990)
The Original: Jungle-set action horror. When Dutch (Arnold Schwarzenegger) and his special forces team head into Central America to take down deadly guerrillas, they encounter an alien predator that's far, far deadlier.
The Radically Different Sequel: Set 10 years after the first film, this slick sequel dumps Dutch in favour of Lieutenant Michael Harrigan (Danny Glover), whose investigations into LA drug cartels leads to a confrontation with the Predator.
Biggest Change: If the first film was an action horror, the second's more of a police procedural that also happens to feature an alien.
Jason X (2001)
The Original: Friday The 13th, one of the first summer-camp-set slasher films. A young Kevin Bacon stars as hack-fodder for a psycho killer who's butchering teens at Camp Crystal Lake.
The Radically Different Sequel: Killer Jason Voorhees is captured and frozen when the US Government fails to find a way to destroy him. Jason wakes up in the year 2455 and soon starts hacking apart annoying future teens.
Biggest Change: It's Friday The 13th In Space ! Until now, the franchise has barely strayed away from Camp Crystal Lake (aside from a later entry disastrously set in Manhattan) and Jason X wants to shake things up.
It also buried the franchise.
Terminator 2: Judgment Day (1991)
The Original: Hard and fast sci-fi that plays around with ideas of fate and the future. The T-800 (Arnold Schwarzenegger) is sent back to 1984 from the future in order to destroy the mother of the saviour of mankind.
The Radically Different Sequel: Sarah Connor (Linda Hamilton) has transformed into a formidable warrior. The T-800 is the good guy. And the T-1000 (Robert Patrick) is hunting John Connor (Edward Furlong).
Biggest Change: This time around, Arnie's the good guy. The scope of Cameron's sequel is also infinitely larger, with more action set-pieces, a longer running time and meatier themes to chew on.
The Devil's Rejects (2005)
The Original: House Of 1000 Corpses , a zombie flick directed, naturally, by Rob Zombie. Two couples fall prey to the savage Firefly family on Halloween.
The Radically Different Sequel: The bloodthirsty Firefly family are back, this time going up against a Texas sheriff and his army of state troopers.
Biggest Change: The baddies from the first film are now the anti-heroes of the sequel, which is all kinds of topsy-turvy and weird.
Just who are we supposed to root for, eh?
Dawn Of The Dead (1978)
The Original: Lean and mean black-and-white classic Night Of The Living Dead. A group of people hole up in a farmhouse which is besieged by legions of ravenous undead.
The Radically Different Sequel: Mass hysteria has gripped the world as the zombie plague recruits yet more innocent victims. Meanwhile, a group of survivors hide out in a mall.
Biggest Change: Romero's second film is big, big, BIG.
Escalating the scale of the franchise, it's a zombie-infested action flick that also adds Technicolor to the mix (y'know, to really make that pumping blood pop on screen).
Batman & Robin (1997)
The Original: Tim Burton's Batman , which made comic book movies cool again and starred Michael Keaton as the Bat. He goes up against Jack Nicholson's manic Joker.
The Radically Different Sequel: Fourth entry in the franchise and contender for the title of Campest Movie Ever. This Joel Schumacher flick stars George Clooney as the Bat and pits him against Arnie's Mr Freeze and Uma Thurman's Poison Ivy.
Biggest Change : How about EVERYTHING? Batman & Robin has about as much in common with the first Batman as a toothbrush does with a tyrannosaurus rex.
Troll 2 (1990)
The Original: Eighties cult flick directed by John Carl Buechler ( The Dungeonmaster ). A San Francisco high rise comes under attack from a troll who's looking for a mystical ring. (Hate it when that happens.)
The Radically Different Sequel: Cult flick widely considered one of the worst films ever made. A family attempt to evade a gang of vegetarian goblins who want to turn them into plants so they can be eaten…
Biggest Change: There isn't a single troll in Troll 2 , which sort of confuses things. Also, the acting's taken a serious downswing…
Gremlins: The New Batch (1990)
The Original: Joe Dante's eighties monster flick starring Zach Galligan as the kid who's given a mogwai for Christmas, which spawns a legion of naughty gremlins.
The Radically Different Sequel: Tongue-in-cheek chuckler that relocates the action to Manhattan, where Zach Galligan's office block is overrun with gremlins.
Biggest Change: Whereas the first film had a wickedly dark sense of humour, the sequel's post-modern and nudge-winky in a far broader sense, frequently breaking the fourth wall.
The Original: A taut, spooky space flick from director Ridley Scott. A group of space truckers happen upon a deadly alien that tears its way through the ship - and their bodies.
The Radically Different Sequel: A gun-blazing war flick ("This time it's war" yelled the tagline) as survivor Ripley (Sigourney Weaver) takes a no-prisoners approach to killing an entire army of xenomorphs.
Biggest Change: Aside from the genre flip, there's not one but hundreds of slathering aliens, and they've been given something of a design tweak. Plus Ripley's got shorter hair now.
Halloween III: Season Of The Witch (1982)
The Original: John Carpenter's genre-defining slasher flick. Laurie Strode (Jamie Lee Curtis) and her babysitter friends are stalked on Halloween by escaped mental patient Michael Myers.
The Radically Different Sequel: A standalone oddity in which the owner of an evil novelties company plots to kill children on Halloween by using booby-trapped scary masks…
Biggest Change: The plot's completely different with no Michael Myers in sight.
Carpenter and producer Debra Hill envisioned the Halloween franchise becoming an anthology series that told a different story with every sequel. When Halloween III flopped, that idea was abandoned.