Actually, Harry did make it into the most secure room in the Dept. of Mysteries at the end of his Fifth Year.
Deatheaters and more attack the Weasley-Delacour wedding, where Harry is laid out, hit by nine killing curses. The result is not a dead Harry, but a Harry whose magic has been purged of its imp...
Another dimensional cross-over Harry? A Dark Grey Harry and a very innocent one combine when Voldemort tries to bend a Light Ceremony to his will. Hopefully not cliché-ridden.
Harry escapes the summer before his fifth year, and comes back with a different attitude.
Take one Harry Potter. Add eleven half-blood and Muggleborn girls. Mix well in one new Hogwarts house. Stir with lots of friends and enemies. Half bake. Serves seven billion.