Saint Matthias is the Apostle chosen by the remaining eleven apostles to replace Judas Iscariot, following Judas' betrayal of Jesus Christ and suicide (Acts 1:23-26). Tradition states he was martyred in Colchis. His feast day is February 24.

Clement of Alexandria wrote this about him:

Not that they became apostles through being chosen for some distinguished peculiarity of nature, since also Judas was chosen along with them. But they were capable of becoming apostles on being chosen by Him who foresees even ultimate issues. Matthias, accordingly, who was not chosen along with them, on showing himself worthy of becoming an apostle, is substituted for Judas.

writings of Clement of Alexandria, Book VI, Chapter XIII