Matthias was, according to the Acts of the Apostles chosen by the Apostles to replace Judas Iscariot. His calling as an apostle is unique, in that his appointment was not made personally by Jesus. According to Acts, he had been with Jesus from his baptism by John until his Ascension. In the days following, Peter proposed that the assembled disciples, who numbered about 120, nominate two men to replace Judas. They chose Joseph called Barsabas and Matthias. Then they prayed, "Thou, Lord, which knowest the hearts of all [men], shew whether of these two thou hast chosen, That he may take part of this ministry and apostleship, from which Judas by transgression fell, that he might go to his own place. Then they cast lots, and the lot fell to Matthias; so he was numbered with the eleven apostles.
His Saint’s Day is 14th May