As much as Judas has become an infamous villain, there is precious little information about him in the Bible — or anywhere else. He first appears in the Gospel of Mark, which was written around A.D. 70, some 40 years after the death of Jesus. Before that, there is no mention of Judas or even a story that clearly outlines the betrayal of Jesus. Instead, the first we get is a brief mention of him in Mark 3:19. There, the writer, naming the 12 disciples, finishes the list by calling out "Judas Iscariot, which also betrayed him."
Even after he steps onto the scene, there isn't much to learn about Judas. There are a few mentions of group activities done by the apostles, of which Judas was almost certainly included. Then, there's the story of his betrayal of Jesus, which the gospels of Matthew and John claim was done for money, while Luke points toward the influence of Satan as the true motivator. For his misdeeds, he dies, and then promptly drops out of the Biblical narrative.
Further complicating things is the fact that Judas was a fairly common name in 1st-century Jewish communities, with some people going by Yehudah or Judah instead of the more Greek-influenced Judas. For the incautious reader, it can be easy to get all of the various Judases and Judahs mixed up with the far more notorious Judas Iscariot.
