 Only two of the disciples can be identified with any degree of certainty : Peter with his iconographic grey hair and beard , and blue and yellow attire , and John ; the young beardless man standing next to Christ . John 's head is reminiscent of Roman sculptures , and it is reflected in the very similar face of another disciple on the right . The person next to this disciple is assumed to be Judas , whose dark and sinister face mirrors that of the tax collector . It has been speculated – first by Vasari – that the face on the far right is a self @-@ portrait of Masaccio himself , as Thomas . 
