If we toss out the requirement for cast continuity (which seems to have happened) then I’ll nominate It Runs in the Family aka My Summer Story (1994), the really bad sequel to A Christmas Story (1983).
Highlander was a great concept that really needed some work with the execution. I don’t think it’s quite to Manos levels of badness, the people behind it were clearly competent and I like it, but remaking it wouldn’t sacrilegious. They could do it right this time and have the alien stuff at the very beginning.
28 Days Later is a brilliant twist on the zombie formula; imaginative, stylish, tense, original.
28 Weeks Later is just derivative garbage; boring, mindless generic drivel.
This is clearly a wrong opinion 
. While it is not great cinema (for various levels of great), it is a good entertaining film and it has some of the best scene transitions in any movie. The scroll downs, the cross-fades and other techniques that they use are really good.
Highlander 2 on the other hand is just not even fun. The only line I liked was “Ashes to Ashes, dust to dust, if you don’t take it out and used it, it’s going to rust” I agree the director’s cut is not that much better than the original theatrical release. It really is the worst immediate sequel.
I would mention Beverly Hills Cop 2 mostly because it was just a hastily put together sequel, but it is still fun so not a bad sequel to the original.
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Fun fact: Highlander’s probably most enduring legacy is the most popular format to play Magic the Gathering was called Elder Dragon Highlander. Highlander formats meant you can only have one copy of each card (“There can be only one”). The format is now called Commander but a lot of people still call it EDH for the original name (and there are other formats that still have Highlander in the name because they only allow one copy of each card).
Lots of good suggestions here, most of which I agree with.
I didn’t like Highlander (sacrilege, I know), but from what I’ve seen Highlander II is beyond awful.
I felt cheated by The Sting II . Not only is it astonishingly bad, but it lacks the one thing that made the original great – it doesn’t capture the “feel” of the period at all. It feels like the 1980s, when it was made.
I definitely agree about RoboCop II, which tried to copy the feel of the original, with its commercials and things, but failed dismally. But RoboCop II would also have been bad if it was made by the creators of the original – read what they had in mind, sometime.
I really did like 2010: The Year we Make Contact. It would have been much better if they’d left out all the voice-over narration, though. It looks bad when compared to the ground-breaking original, which is a bit unfair, really. Also Peter Hyams couldn’t really do what Kubrick did in making the people practically all ciphers – this is a film that is about people and their interactions (generally seen as a GOOD thing for a movie), and Hyams was following in Clarke’s footsteps, not collaborating with him the way Kubrick was-- the book had already been written. I also like that the spacecraft actually moved the way spacecraft should. In most movies the ships swoop and glide as if they’re in an atmosphere. (In this one the ship IS in atmosphere for a time, so they can get away with that. I also won’t begrudge Hyams the few times you hear a space ship engine roar). I really like the way they depict the Discovery rotating end over end and covered in dust – that is pretty much what I’d expect. 2010 gets a solid grade for a hard science fiction movie with mystical touches.
City Slickers II: The Secret of Curly’s Gold was pretty bad. The hoary trope of bringing back a killed-off character by having him be a twin brother of the original was never more abused.
I haven’t seen it, but by all accounts Joker: Folie a deux was incredibly awful.
I am surprised with everyone crapping over Robocop 2 no one has mentioned Robocop 3 which was even worse
I have to say that I agree that Airplane II was pretty damned god, especially considering that it WASN’T made by the same people. That sort of humor is hard to carry off, and I’m impressed that Airplane II has much the same feel as the original.
To see how bad it could have been, consider how the makers of Robocop II utterly failed to reproduce the black humor of the original. All their hack commercials fall flat.
One sequel that isn’t as good as the original film, but which I can’t blame the filmmakers for, is Son of Kong. RKO gave Schoedsack and Cooper a tiny fraction of the budget of King Kong and hardly any time to make the film. Considering that they had not only a lot of time to make the original, and could also draw of ideas dreamed up for the aborted Willis 'Brien film Creation (as use the animation models and sets built for it), that’s asking a huge amount. They re-used what they could, came up with a quick plot, and were forced to rely on a huge amount of padding in the first half of the movie. That it turned out as good as it did is a tribute to the creativity of the filmmakers. But it could have and should have been better – but RKO wanted a quick cash grab.
The record for most immediate might be Son of Kong. It came out the same year as King Kong
It’s not the worst by far but a it was a step down in quality.
Despite its silliness, the original Fast and The Furious was effectively a documentary on street racing with unrealistic effects and unrealistic plot involving organized crime added in. The ‘nobody’ who comes in last in the first race is a champion street racer who acted as a consultant for the movie.
The later movies ditch all ties to reality and are exponentially more stupid.
So, how did they end up being superheroes in the later movies?
Hmm, it’s probably better if I don’t think about it.
Family
“Jaws the Revenge” has my vote. Not only is the movie itself poorly made and ratty, the premise that a shark out there would actually be swimming around looking for revenge against a land dwelling human is more than totally absurd.
Porky’s II: The Next Day
Hmmm…so it is 12 years after the original, which is the good one. Is that an immediate sequel? Or are we talking about it as a sequel to Jaws 3D, which was 8 years after the original and four years before Revenge.
I don’t think it totally counts, though it is famously terrible. It’s pretty much unfinished, even.
“Forget the airlines. The fastest way to Bermuda is shark!”
Definitely not a sequel to a great movie.
I’d argue that PLANET OF THE APES was a classic, and that BENEATH — wasn’t.
I forgot the comedian, but one in the past observed thus:
“I recently did see the best Kickboxer movie ever! It was called ‘Kickboxer’…
Later, I did see the worst Kickboxer movie ever!… It was ‘Kickboxer 2…’”
The first movie with Van Damme was not a critical hit 
, but it was considered a good popcorn movie according the Tomatometer,
Kickboxer 2 was missing Van Damme, and it was a rushed production, leading to the critics giving it worse reviews than the original and even with the popular vote, it failed miserably.
Ooh, good shout. I know there is some love for Beneath, but I just don’t see it. It is very very boring. The first, as you say, is a very good film sadly spoiled because literally everyone who watches it these days must know the ending.
This is a good call. Maybe a decade ago I planned on watching all the older movies. Loved the first one and just quit after beneath it was so bad. I hear it gets good again, but didn’t want to watch through the slop first.