Horror movies are great at churning out sequels, and most of the time, each sequel sees the quality dip, the budgets reduced and the original stars moving on to better things.
When it comes to most classic films, you simply can't imagine anyone else but that actor playing the characters.
Tom Hanks as Forrest Gump, Harrison Ford as Han Solo or Keanu Reeves as Neo seem like those actors were in mind when the film was being thought up, yet those weren't the first choices for those roles.
