Starship Troopers- does it count if you just forget there ever were sequels?
Kinda like Tremors. Love that first movie, can't believe there were SEVEN of them.
Fast and the Furious is another like Jurassic Park for me. Would it have been better if they stopped after 1? Maybe. But then we would have never gotten Fast Five.
I think every classic Disney movie has multiple sequels. I have Cinderella 2 and 3 sitting on my shelf because I forgot to cancel an order; I remember really like Aladdin 2: The Return of Jaffar.