Where is Matthias in the Bible?

Saint Matthias is only mentioned by name once in the New Testament in the Acts of the Apostles. Acts 1:21-26 tells of the full account when Saint Matthias was chosen to become the Apostle who would replace Judas Iscariot.

[Peter said], “So one of the men who have accompanied us during all the time that the Lord Jesus went in and out among us, beginning from the baptism of John until the day when he was taken up from us—one of these men must become with us a witness to his resurrection.” And they put forward two, Joseph called Barsab’bas, who was surnamed Justus, and Matthias. And they prayed and said, “Lord, who knowest the hearts of all men, show which one of these two thou hast chosen to take the place in this ministry and apostleship from which Judas turned aside to go to his own place.” And they cast lots for them, and the lot fell on Matthias, and he was enrolled with the eleven apostles.