"My Immortal" is a Harry Potter fanfic authored by Tara Gilesbie (under the penname of "XXXbloodyrists666XXX"), with assistance from a friend named "Raven" (penname "bloodytearz666") and an additional, "unofficial" contribution from an anonymous "hacker."
The story is infamous for its lack of quality and potential satirical purpose, along with the minor Internet phenomenon of dramatic readings and interpretations. Sadly, it was the single most reviewed story on Fanfiction.net and, by extension, probably the most read and talked about fanfic in existence. The story is no longer on Fanfiction.net, but numerous other sites now host it.
For a list of administrators, see here.