Will the REAL 12th Apostle Please Stand Up!

Since the 2nd Century, there has been much debate on who the real 12th Apostle was after Judas Iscariot killed himself. Was it Mathias whom the Apostles prayed about and drew lots to see who Jesus would choose? Or was it Paul who Jesus appeared to on the road to Damascus and specifically called to be an Apostle to the Gentiles? Will the REAL 12th Apostle please stand up!