When it comes to the best sci-fi franchises out there, they all have one very big thing in common. They all have very memorable villains and very memorable heroes. The best of the best really can't have just one or the other. The best movies need to make sure and have both in order to play off one another. Of course, even when a movie has a good guy and a bad guy, there isn't a guarantee that the characters in that sci-fi movie are going to be memorable for generations. That's why there are so few heroes from these movies that really stand the test of time.