Which of the following is NOT a summon in the game "South Park: The Stick of Truth"?

Towelie is not a summon in the game South Park: The Stick of Truth because he does not possess any extraordinary abilities or powers that could aid the player in battle. Instead, Towelie serves as a recurring character that provides humorous insights or tips throughout the game. While other characters like Mr. Slave, Jesus, and Mr. Hankey can be summoned to join the player's party and offer unique abilities, Towelie is not included as a summon option in the game.