HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH, dubbed Thirty Hs for ease of spelling and pronunciation, is either one of the worst or one of the best Harry Potter fanfics ever. Similarly to My Immortal, it's probably a Troll, and has become notorious in the fandom. It can be read here, and is NSFW and NSFB.
It's pretty much impossible to summarise accurately, but to take the most basic premise, Harry Potter has inexplicably gained godlike powers and goes around killing people and smashing up planets for no readily apparent reason. Along the way he encounters demonic astronauts, astral vampires, some highly unexpected inquisitors, and a headless scientist who appears in an apparent Pokémon reference.
- "Harry, you must rock the fuck out."