The Curse Of The Cat People (1944)
The Original: Horror flick following Irena (Simone Simon), a Serbian woman who believes that she's the descendant of a special breed of person who can transform into cats whenever they're, um, 'excited'.
The Radically Different Sequel: A psychological thriller with all the same characters but a totally different plot as six-year-old Amy makes an imaginary friend who turns out to be the ghost of Irena…
Biggest Change: There are no actual cat people in the film, other than the ghost of Irena…
Critters 4 (1992)
The Original: A fun Gremlins bandwagon-hopper set in rural Kansas, where a farm is terrorised by invading aliens called Critters. It's not long before the bodies start piling up.
The Radically Different Sequel: The action's moved to space, where the franchise's unlikely hero Charlie (Don Keith Opper) attempts to eradicate the Critters once and for all.
Biggest Change: The setting is no longer Earth, but a space station for a film that clearly wants to be Alien (just check out the computer Angela), but is nowhere near as clever or atmospheric.
Shock Treatment (1981)
The Original: Rocky Horror Picture Show aka one of the greatest musicals ever made. Tim Curry stars as Dr Frank N. Furter, a transvestite who plays host to young couple Brad and Janet when they get a flat tyre during a storm.
The Radically Different Sequel : A bizarre follow-up in which Brad and Janet's hometown has been transformed into a giant game show - and they're incarcerated as unwilling contestants.
Biggest Change: Though some of the same characters appear - notably Brad and Janet - they're played by different actors, so they might as well be totally different characters anyway.
The Howling II (1985)
The Original: A knowing werewolf flick starring Dee Wallace as reporter Karen White, who's sent to an isolated retreat with her husband after a traumatic event. Problem is, the retreat is secretly home to a pack of werewolves…
The Radically Different Sequel: Karen's brother Ben (Reb Brown) discovers that his sister was a werewolf when he meets the mysterious Stefan Crosscoe (Christopher Lee).
Biggest Change: Philippe Mora's sequel plays it straight, and the results are less than thrilling. What happened to the fun tongue-in-cheek vibe of the first film?
Also, the prosthetics are shocking.
Tremors 4: The Legend Begins (2004)
The Original: Comedy horror starring Kevin Bacon. He's part of a band of small-towners who are targeted by underground-dwelling monsters called graboids.
The Radically Different Sequel: A made-for-TV prequel set in 1889. The inhabitants of Rejection Valley attempt to fend off the graboids with limited fire power…
Biggest Change: Though it's technically a prequel, it's also completely different from the previous three Tremors flicks thanks to its 19th Century setting.
Blair Witch 2: Book Of Shadows (2000)
The Original: A phenomenon as much as a movie as directors Eduardo Sánchez and Daniel Myrick convince everybody that the Blair Witch is real for a black-and-white scarefest.
The Radically Different Sequel: The Blair Witch goes Goth as a group of friends head to Maryland to research the witch for their book. After spending the night at the Parr house, they all wake up with no memory of the night before…
Biggest Change: The found footage aspect is all but abandoned in favour of a far more conventional approach to horror movie-making. Snore.
The Chronicles Of Riddick (2004)
The Original: Pitch Black , an Alien-esque sci-fi horror set on a remote alien planet where scary criminal Riddick (Vin Diesel) is the only one with the skills to survive the planet's deadly alien populace.
The Radically Different Sequel: A big, bloated epic that attempts to turn Riddick's (yes) chronicles, into a massive sci-fi franchise. This time, Riddick goes up against an evil Necromonger and helps out Judi Dench.
Biggest Change: Riddick was always an anti-hero, but Chronicles takes it to another level, watering him down in order to put him at the centre of a franchise. It doesn't work.
Wes Craven's New Nightmare (1995)
The Original: Dream-weaving slasher flick following the children of Elm Street, among them Nancy (Heather Langenkamp), who are haunted by Freddy Krueger (Robert Englund), the murderer whom their parents killed.
The Radically Different Sequel: Released 11 years after the original A Nightmare On Elm Street , Craven returns to close the franchise with New Nightmare, which is set in the 'real world' and stars Langenkamp as herself.
Biggest Change: Ahead of his work on Scream , this was Craven doing post-modern horror and brilliantly blurring the lines between fact and fiction.
The Raid 2 (2014)
The Original: Unexpected smash hit of 2011 and the second film from Welsh director Gareth Evans. Iko Uwais is Rama, a rookie sent in to storm a high rise that's been commandeered by a crime lord. Soon, body parts fly.
The Radically Different Sequel: Picking up where the first film left off, Rama is this time recruited to infiltrate a Jakarta crime syndicate while also attempting to protect his family from corrupt cops.
Biggest Change: Naturally, the action's even more ambitious and breathtaking, but the decision to open up the franchise's landscape is the biggest change.
Conan The Destroyer (1984)
The Original: Conan The Barbarian , which introduced Arnold Schwarzenegger as the muscular loincloth-lover. He seeks revenge against snake cult leader Thulsa Doom (James Earl Jones) for the death of his parents.
The Radically Different Sequel: A family-friendly fantasy. Conan is tasked with transporting Princess Jehnna (Olivia d'Abo) to a fortress where a mystical crystal has been hidden.
Biggest Change: Where the first Conan was an adult fantasy that didn't skimp on the gore, the sequel's as family-friendly as they come. Which is just odd if you ask us.