While Harry brings courage and heart, and Ron brings, well, something, to the main trio of the "Harry Potter" saga, Hermione Granger is unquestionably the brains behind the organization. Starting out as Harry and Ron's annoying classmate constantly out to prove she was the smartest student in the year, Hermione was a key part of Harry's victory over Voldemort in "Harry Potter and the Philosopher's Stone."
Her MVP status remained intact over the next six books. Whether discovering the entrance to the Chamber of Secrets and the nature of the monster lurking within, realizing the secret that Professor Lupin was trying to hide about himself, or practicing spells with Harry relentlessly so he wouldn't get immediately slaughtered in the first round of the Triwizard Tournament, Hermione was always the most reliable and useful friend to have in your corner. Apart from looking out for her immediate circle of friends, Hermione also had a deep sense of empathy for all creatures.
She was the first one in the series to recognize the cruelty inflicted on house-elves by their owners and actually tried to do something about it. There was a running joke throughout the series that Hermione's intelligence should have gotten her placed in Ravenclaw instead of Gryffindor. But the truth is, her courage, brains, empathy, and ambition would have made Hermione a credit to any house lucky enough to have her.
