The 'Little House' books Classics.

The Mennyms I don't know anyone else who's read this series but I absolutely loved it.

Animorphs I started reading Animorphs because in 3rd grade I had to do a "sci-fi" book report. I threw a fit because I didn't like sci-fi...and only agreed to read this because it had a dolphin on the cover. A decade and a half later...my favorite TV shows are Star Trek and Supernatural and I've never looked back.

Harry Potter This list would not be complete without the Harry Potter books. I won't get into my thoughts on the last two, but the first 5 were a golden part of my adolescence and will always have a special place in my heart.