@ Cog

Judas is mentioned in the Gospel of Thomas as in the Nag Hammadi gnostic gospels as Jesus' best friend. From that early textual mention 2nd Century authors probably based their "gospel" (*which is actually an account of verbal exchanges ) .
Understand that every "gospel' up until the mid 3rd century (* when they combined the gospels and started to flesh out the stories) was in the authors minds the "only" gospel, the one true account of Jesus' life and death. Matthew and Luke were entirely based on Mark, but intended for different audiences, Luke for the Hellenistic Greeks and Matthew (sans the first two chapters) for the Messaniac Jewish "Christians". It wasn't an intentional dichotomy from a copy of a "true story" it was purely where the scribes lived that influenced the style and the story line to appeal to the local audience.
The gospel of Judas ( also called the Repentance ) was a Gnostic gospel i.e one that rejected the claim that Jesus was born divine, but rather lived and died as a good man who obeyed the laws and was elevated by god after his suffering and death. This differs slightly from the Jewish "Adoptionist" position who maintained that Jesus was an ordinary man but adopted as a son by god because of his adherence to the "Law" (Torah)and went straight to heaven after his physical resurrection. Both Gnostic and Adoptionist positions negate the need to invent such an untenable theological position as the "Trinity". Hemce they were prosecuted and destroyed along with all their works when the Pauline church gained ascendancy.

*The Gospel of Judas is a Gnostic gospel whose content consists of conversations between Jesus and Judas Iscariot. It is thought to have been composed in the second century by Gnostic Christians, not by the antagonist Judas, since it contains late-2nd-century theologyWiki

(Edit: Excuse the lack of citation and detail, its 5am and I have a cat demanding attention, so my memory will have to do. Ask if you really want sources)

(Added) As the cat decided to bugger off on feline business after inhaling down a quantity of raw meat...I chanced upon an article condemning the treatment and translation of the Gospel of Judas by National Geographic...this para caught my eye and I immediately thought Diotrephes would love this....from the New York Times" So what does the Gospel of Judas really say? It says that Judas is a specific demon called the "Thirteenth." In certain Gnostic traditions, this is the given name of the king of demons - an entity known as Ialdabaoth who lives in the 13th realm above the earth. Judas is his human alter ego, his undercover agent in the world. These Gnostics equated Ialdabaoth with the Hebrew Yahweh, whom they saw as a jealous and wrathful deity and an opponent of the supreme God whom Jesus came to earth to reveal.

Whoever wrote the Gospel of Judas was a harsh critic of mainstream Christianity and its rituals. Because Judas is a demon working for Ialdabaoth, the author believed, when Judas sacrifices Jesus he does so to the demons, not to the supreme God. This mocks mainstream Christians' belief in the atoning value of Jesus' death and in the effectiveness of the Eucharist.

How could these serious mistakes have been made? Were they genuine errors or was something more deliberate going on? This is the question of the hour, and I do not have a satisfactory answer.

I am so intrigued now I wil have to go back to the original and read for myself...bugger it Cog...why do you have to be so interesting at this hour?