Myth: He hung himself from a tree.
Truth: He fell onto a sword.
Matt 27:5 says:
And he cast down the pieces of silver in the temple, and departed, and went and hanged himself. KJV
It seems pretty clear from this verse that the myth is correct. Even upon looking up the word "hanged" in the Greek, apagchomai, to choke, strangle or throttle, it seems clear cut. Unfortunately this is the only gospel that says anything about it.
The answer lies in Acts 1:16-18:
Men and brethren, this scripture must needs have been fulfilled, which the Holy Ghost by the mouth of David spake before concerning Judas, which was guide to them that took Jesus. For he was numbered with us, and had obtained part of this ministry. Now this man purchased a field with the reward of iniquity; and falling headlong, he burst asunder in the midst, and all his bowels gushed out. KJV
This does not happen from being hung by the neck! Let's see how some other versions handle this verse.
Acts 1:18-19 (Now this man acquired a field with the price of his wickedness, and falling headlong, he burst open in the middle and all his intestines gushed out. NASU
Acts 1:18 "As you know, he took the evil bribe money and bought a small farm. There he came to a bad end, rupturing his belly and spilling his guts. (from THE MESSAGE: The Bible in Contemporary Language © 2002 by Eugene H. Peterson. All rights reserved.)