Mark 9 is the ninth chapter of the Gospel of Mark in the New Testament of the Christian Bible. It begins with Jesus' prediction that "I tell you the truth, some who are standing here will not taste death before they see that the kingdom of God has come with power". The chapter then recounts the transfiguration of Jesus, a healing miracle, and Jesus' teaching about the return of Elijah, humility and temptation.

The Gospel of Mark is the second of the four canonical gospels and one of the three synoptic Gospels. It tells of the ministry of Jesus from his baptism by John the Baptist to his death, the burial of his body, and the discovery of his empty tomb. It portrays Jesus as a teacher, an exorcist, a healer, and a miracle worker, though it does not mention a miraculous birth or divine pre-existence. He refers to himself as the Son of Man. He is called the Son of God but keeps his messianic nature secret; even his disciples fail to understand him. All this is in keeping with the Christian interpretation of prophecy, which is believed to foretell the fate of the messiah as suffering servant.