What has the author R L Pfaltzgaff written?

It seems you might be asking about the author R.L. Stine, not Pfaltzgaff. He is a very well-known author, particularly for his work in horror fiction.

R.L. Stine is most famous for:

* Goosebumps: A popular children's horror series with over 200 books.

* Fear Street: A young adult horror series set in the fictional town of Shadyside.

* The Nightmare Room: A television series based on his Goosebumps stories.

He has also written many other horror books for children and young adults, including:

* The Babysitter's Club: Night of the Living Dummy

* The Mostly Ghostly Series

* The Haunting Hour Series

If you meant a different author, please clarify the name and I'd be happy to help!