The Orthodox Church commemorates today the Apostle Matthias as well as Martyrs Julian, John, James (Jacob), Alexius, Demetrius, Leontius, who remained steadfast in their Orthodox faith, as it is the case for many Christians around the world today.
The Apostle Matthias is the twelfth Apostle, who was chosen by the eleven apostles by lot in order to replace Judas Iscariot, who became a traitor. Immediately after the Ascension of the Lord, the Apostles gathered and, at Peter’s instigation, “they chose Joseph called Barsabas” (whose surname was Justus) and “Matthias”. After praying together, they cast lots, and “the lot fell to Matthias”; so he was numbered with the eleven apostles. [Acts 1:26]
No further information about Matthias is to be found in the New Testament. He probably was originally one of the 70 Apostles. Legend has it that Matthias was the first person, who preached in Judea and then in Ethiopia. He is said to have completed his missionary work there and then to become a martyr, after being crucified by idolaters. According to other legends, he was killed either in Sevastopol or in Jerusalem.
Source: Church of Cyprus