Guess Who? #14

As usual, here are the rules: this is an (educated) guessing game where every Friday I post five facts about an author, each one a little more revealing then the previous one. I'll give you the weekend to try and figure out who I'm talking about, and the Monday following, I post the answer:This author is female.

1. This author is female
   
2. She wrote a very popular series for teens.
3. Author X also wrote a novel for adults.
4. If you simply guess now, the first author that pops into your head is probably correct.
5. Her whole best-selling series is being turned into a collection of movies.

This post maybe a little vague at first glance, but trust me when I say the author is quite obvious!!