Which apostle was chosen by casting lots to replace Judas Iscariot? The answer is Matthias.
After Judas Iscariot’s death, the Book of Acts says that the remaining apostles and other disciples gathered in Jerusalem to restore the number of the Twelve. Peter proposed selecting someone who had followed Jesus from his baptism by John through the Ascension. Two candidates were nominated: Joseph Barsabbas, also called Justus, and Matthias.
The group prayed for God to reveal the choice and then cast lots. The lot fell to Matthias, who was consequently counted among the apostles. This is the only appointment of an apostle by lot described in the New Testament, and the account appears in Acts 1:15–26.
Matthias is easily confused with other early Christian figures. He is not one of the original Twelve named in the Gospel lists, because he joined the group after Judas’s departure. The canonical New Testament gives no further biography of him, so later traditions about his missions and death vary. Some early writers even associated him with other figures, but those identifications are not settled.