Scream
This 1996 thriller might be a little far fetched, but it certainly is unsettling. Stars like Neve Campbell, Drew Barrymore, David Arquette, Courtney Cox, Rose McGowan all show up in this film that pushes the boundaries of modern moviemaking and coming of age films all at once.
Jaws
Jaws was one of those films that completely changed an entire generation of moviegoers. The sheer terror that older folks express about the mysteries of the ocean and the dangers of sharks are both unwarranted and surprisingly demonstrative of a positive movie premise done well. Just remember, it's "You're gonna need a bigger boat," not "We're gonna need a bigger boat."