Hermione Granger. Harry's friend, smart, brave and idealistic.

Hermione Granger is one of Harry's closest friends, and a valuable member of Gryffindor house. Top of almost every class, Hermione has few contemporary equals in terms of sheer magical knowledge. Since both of her parents are muggles, dentists in fact, her exceptional skill at spellcraft is interesting. It is probably due in most part to her extremely studious nature and natural academic brilliance. In any case, were it not for Hermione's ability to effectively recall exactly the right charm at the right time, and solve puzzles like the nature of the Basilisk, Harry would likely have been a goner long ago.

When Hermione first arrived at Hogwarts, and met Harry and Ron on the train, she was something of an insufferable know it all. Before long, however, she became drawn into the events surrounding the Philosopher's Stone and decided a little rulebending to be needed in order to fit in at school. She tends to feel that if they can battle Voldemort, and stay alive without breaking any school rules, then they should make their best efforts to do so.

In the second year, Hermione was petrified by the Basilisk, but not before working out what it was, and managing to warn Harry and Ron in a scribbled note. Without that help, who knows what might have happened.
Hermione attended the Yule ball in their fourth year with Viktor Krum, international quidditch player and student of Durmstrang, one of Hogwart's rivals in the Triwizard Tournament. This seemed to occasion not a little jealousy in Ron, although it's hard to say which of them he was jealous of.

Fifth year saw Hermione named Gryffindor prefect, unsurprisingly, and necessitated a running battle between her and the Weasley twins over their testing of experimental sweet recipes on innocent first years. Luckily no hostility arose and by the end of a year under Professor Umbridge's thumb, Hermione seemed positively enthusiastic about their troublemaking schemes.