Answer:
Judas Iscariot, the man who betrayed/ sold Jesus to the Sanhedrin.
Explanation:
Dante Alighieri's "Inferno" is part of his "Divine Comedy" which has three parts- Inferno, Purgatory and Paradise. The ninth circle of hell is seen in the "inferno" part of the book.
In the book, Dante was undertaking a spiritual journey when he got lost and was sent Virgil to guide him. Together, they went through the various levels of hell, meeting some people they know and also interacting with the people, sinners who are all deserving of being kept in hell. In the last canto, Canto XXXIV, we see them being in the Ninth circle of Hell where they were greeted by the sight of a monster who was chewing the heads of the 'cheaters' of their benefactors. In the middle was Judas Iscariot, who sold Jesus Christ to the enemies and led to his arrest and crucifixion, while the other two sides contain Brutus and Cassius, the killers and betrayers of Caesar.
