Matthias the Apostle was selected after Christ's resurrection to replace Judas Iscariot and restore the number of apostles back to twelve. Judas was among the original apostles chosen by Jesus during our Lord's ministry (Mt 10:1-4), but he eventually betrayed Jesus to those who orchestrated his death. Afterwards, Judas was filled with remorse and committed suicide.
After the Lord Jesus rose from the dead he appeared to the remaining apostles and instructed them to wait for the power of the Holy Spirit. While waiting, Simon Peter told the believers that they must choose another disciple to take the place of Judas. Peter said, "...Therefore it is necessary to choose one of the men who have been with us the whole time the Lord Jesus was living among us, beginning from John’s baptism to the time when Jesus was taken up from us. For one of these must become a witness with us of his resurrection." (Acts 1:15-26). The group nominated Barsabbas (Justus) and Matthias. After praying they drew lots and the lot fell to Matthias. He was "added to the eleven apostles" bringing the number back up to twelve.
This is the last we hear of Matthias in canonized Scripture. Accounts of his life from tradition are contradictory. Some say he ministered in Judea and some say he went to Ethiopia. Some say that Matthias died of old age and some say he was stoned at Jerusalem then beheaded. Regardless of his personal history, we do know this: he faithfully followed Jesus from the beginning; he was recognized as being worthy of apostleship; and he received this calling although he knew what it might cost him.
Did Matthias ever wonder why he wasn't chosen by Jesus with the first group of twelve? Perhaps it was difficult being the second choice; nevertheless, Matthias faithfully stayed with Jesus from the beginning through the end. Matthias' faithfulness was additionally evident when he willingly accepted the apostolic responsibility of caring for God's people without fanfare or comment. He was a true pastor who took up his cross and followed Christ in relative obscurity.
That is the song and inspiration of millions of Christians throughout the world. Not many of us will be famous, powerful influencers for Jesus. Not many of us will be canonized as "saints". That's probably just as well, isn't it? Let's take up our calling to be unsung heroes who faithfully follow the Lord Jesus Christ wherever he may lead. May the true and faithful Saint Matthias be our inspiration.