In the game Enter the Gungeon, which one of these is not a playable character?

In the game Enter the Gungeon, The Wizard is not a playable character. The Wizard does not possess unique abilities or mechanics as other playable characters do, and therefore cannot be selected for gameplay. Instead, players can choose from various other characters, each with their own distinct playstyles and abilities, making The Wizard unavailable for selection as a playable character in the game.