Did someone named Carolyn Keene really write ALL of the Nancy Drew books?

[defy_gravity80808]

It's just that there are sooooooo many, it seems impossible that the same person wrote all of them. Is it really a bunch of authors writing under the same name? Or did Carolyn Keene really write them all?
Or is it a pen name? Or what?

 

[dirrtygirl.am15]

The whole series is written by maybe a hundred authors. Carolyn Keene is just a pen name for all of those authors.