Upvote:0
There is Secret Mark. Its authenticity is debatable, but it purports to be the advanced version of the Gospel of Mark.
Upvote:0
There is a collection of writings labeled The Nag Hammadi Library which were discovered in Egypt in 1945. This include the Apocryphon (or Secret Book) of John. Many of these books are suspected of being gnostic. You did specify "purported" books were to be included.