Following along in a series of lectures by Prof. Bart D. Ehrman of the University of North Carolina, I've come to his examination of the historical character of Judas.
Now Ehrman is certainly no fundamentalist: He is happy to point out many places in the New Testament where two or more stories are flat out inconsistent and cannot all be true. But he is a good historian, and knows how to use his historical sources to get at the most likely truth, rather than what best serves an axe one has to grind.
He notes that there are differing mutually incompatible accounts of Judas's death both in Matthew, in Acts, and several other early Christian sources. But he also notes that there are multiple attestations of Judas's existence, his discipleship to Jesus, and especially, of his betrayal of Jesus. The last, Ehrman notes, is most emphatically not something that early Christians would be likely to make up: That a rabbi's disciple would betray him is not a very strong recommendation of the rabbi. The correct historical conclusion is that this guy really did betray Jesus in some way.