We discussed that the apostle Matthew - the former tax collector - wrote the Gospel of Matthew. What happened to him afterwards?
Scripture is silent on the fate of most of the apostles, and Matthew is no different. He is not mentioned in any of the epistles (letters) and the next time we see him after the Gospels is in Revelation, where John sees all 12 apostles standing with the 12 patriarchs around the Throne of God.
But there are traditions that have been handed down. It is important to remember that traditions are not authoritative, and could be wrong. But they can still be useful, if used cautiously. Fox's Book of Martyrs reports this about Matthew:
He wrote his gospel in Hebrew, which was afterwards translated into Greek by James the Less. The scene of his labors was Parthia, and Ethiopia, in which latter country he suffered martyrdom, being slain with a halberd in the city of Nadabah, A.D. 60.
Ethiopia is a land in eastern Africa, while Parthia is a region now in north-eastern Iran. A halberd is a spear with an axe-attached - given the regions Matthew was working when he would have died, it is more likely to have been a simple spear.
So Matthew, like most of the apostles, died a martyr for the Gospel of Christ.