I read the entire Bible in my teen years as if it was a religious quest. I then found out about a class of books called the Pseudepigrapha or Apocrypha and I began reading them. My interest in them was mainly to find out details that the Bible left out. Of course, the authenticity of these books are disputed because of their late dating from the events that they described, but nonetheless they report on events that the Bible leaves out. My favorites are the books of Enoch, especially the first one. I really wanted to know more about the fallen angels and the Nephilim which is referenced in Genesis 6. I thought the book of Enoch was a place to get that information.

I've also read the Jubilees, the Testament of Adam, the Apocalypse of Abraham, the Life of Adam and Eve, and a few others. Most of these books were collected in one volume called The Old Testament Pseudepigrapha: Apocalyptic Literature & Testaments edited by James H. Charlesworth.

I've also read the Gospel of Thomas.