In South Park , Mysterion is revealed to be Kenny McCormick.

Quick Scoop: Who Was Mysterion?

Mysterion starts out as a mysterious vigilante superhero who appears alongside Cartman’s alter ego “The Coon” in the episode “The Coon.” His true identity is intentionally kept hidden at first to fuel fan speculation and forum debates over who was behind the mask.

In the later storyline “Coon and Friends” and the episode “Mysterion Rises,” the show finally confirms that Mysterion is Kenny McCormick, and his “superpower” is the same one fans already know: he dies and comes back to life, with everyone else forgetting it happened. This immortality and the trauma that comes with it become core parts of his darker, brooding superhero persona.

How the Mystery Played Out (Fan & Forum Angle)

Before the reveal, fans argued online about whether Mysterion was Clyde, Craig, Stan, or someone else, picking apart clues like body shape, classroom scenes, and behavior. The creators originally liked the idea of never clearly revealing who Mysterion was, using it as an ongoing in-joke similar to the mystery of Cartman’s father.

When Kenny is finally confirmed as Mysterion, it retroactively explains why the character is so serious, self-sacrificing, and weirdly fearless about death in the “Coon and Friends” arc. Since then, official wikis and studio character guides list Mysterion’s real name as Kenny McCormick.

TL;DR: Mysterion’s secret identity in South Park is Kenny McCormick, whose power is that he constantly dies and comes back to life, which the show leans into in the “Coon and Friends” episodes.

Information gathered from public forums or data available on the internet and portrayed here.