The Lord of the Rings, if it counts as a book series (to me, it's just one long book, even though it was published in 3 parts). If not, The Belgariad series by David Eddings is next in my list. And, of course, Harry Potter!
It was a really tough decision, because there are many interesting classes! But I finally applied for: -Fantastic Beasts -Fantastic worlds and where to find them -Journey of the hero And I've been accepted in all 3, so... I'm happy :) I'll consider joining a 4th class if I have time.