Since El Capitan has posted the answers to the ones no one guessed, I'll post some hints and give everyone a last chance.
#1: This is probably obscure for most people. It was a movie starring Stacey Keach but he did not speak this line. The movie was directed by the man who originally wrote the book, and the book had a different title than the movie.
#2: This line in context is not a request or a plea, it is a threat. It's from a movie starring Nicolas Cage but he did not speak that line.
#3: Another vengeance flick starring someone who became a really famous and respected actor later on.
#5: Another film based on a Lovecraft story.
#6: I'm surprised no one got this one. Another movie starring someone who became a lot more famous later on, and is a cult favorite for many people. The ending credits promised a sequel but it never happened. I chose this quote because most of the other good quotes would be far too easily recognizable.
#9: No one is going to get this, but here's a hint anyway. An obscure slasher film centered around cannibalism and a Yeti hunt.
#15: This is an enormously famous comedy, with many well-known actors, and is loaded with great quotes, many of which would be immediately recognized by most movie fans.