Who was chosen to replace Judas Iscariot among the apostles?

Matthias was chosen to replace Judas Iscariot among the apostles, as recorded in Acts 1:15-26. After Judas' betrayal of Jesus and subsequent death, Peter stood up among the believers (about 120 in number) and proposed that a replacement be chosen to restore the number of apostles to twelve. The criteria were that the candidate must have been with the group throughout Jesus' ministry, from the baptism of John until the Ascension.

Two men were nominated: Joseph called Barsabbas (also known as Justus) and Matthias. The apostles prayed, asking God to show which of the two He had chosen, and then cast lots. The lot fell on Matthias, and he was numbered with the eleven apostles (Acts 1:26).

The other options are incorrect. Paul (formerly Saul of Tarsus) became an apostle through a direct encounter with the risen Christ on the road to Damascus (Acts 9), but he was not one of the original Twelve and was not part of this selection process. Silas was a prophet and missionary companion of Paul (Acts 15:40) but was never counted among the Twelve. Barnabas was an important early Church leader who accompanied Paul on his first missionary journey (Acts 13-14) but was likewise not chosen as Judas' replacement.