Luna Lovegood

Aptly named, and known for being a little more eccentric than most, Luna possesses a slightly off-kilter, yet composed persona. The Ravenclaw student is among the first to believe Harry when he claims that Voldemort has returned; she joins Dumbledore's Army, sparking the beginning of a strong friendship with the protagonist trio. Like a Patronus that appears in dire situations, Luna's presence never fails to procure hope and solace for Harry even in the darkest hours.

25 points for the FIRST person to tell me what is Luna's patronus.