The Thirteenth Man
Alternate-universe science-fiction Daria fanfic by The Angst Guy. Through a quirk in quantum physics, Mack Mackenzie has become a super-powered hero on the level of Superman, but he hides his true identity and has not, at the story's start, revealed himself to the general public.
Tied for "Favorite Science Fiction" story in the 1st Daria Fanworks Awards.
In the Author's Notes, TAG said it was partly inspired by how Mack was "without a doubt the only non-dysfunctional male in the entire Dariaverse" and wasn't appearing in many fics at the time.