Guess Who? #2

I know, I know - I'm a day late. I really am sorry! I'll be on time next week! I promise!

Anyways, here is how this meme works: Every Friday (or in this case, Saturday) I will post five facts about an author, each one a little more revealing then the one before, and I will give you the weekend to try and figure out who I'm talking about. The Monday following, I will post the answer. Sound like fun? If so, then here is this week's:

1. Many authors have written books in this series.
2. The pen name is a female author.
3. There are over 200 books in this series.
4. They were first published in the 1930's.
5. Game companies have taken the main character and put her in several PC games, a Game Boy game and a few DS games.

So, who do YOU think it is?