Hermione Jean Granger is a Muggle-born, Gryffindor student[2] who becomes best friends with Harry Potter and Ron Weasley. J.K. Rowling states that she was born on 19 September 1979[1] and she was nearly twelve when she first attended Hogwarts.[3] She is an overachiever who excels academically, and is described by Rowling as a "very logical, upright and good" character.[4] Rowling adds that Hermione's parents, two Muggle dentists, are a bit bemused by their odd daughter but "very proud of her all the same."[5] They are well aware of the wizarding world and have visited Diagon Alley with her. Hermione was originally intended to have a sister, but the planned sibling did not make an appearance in the first Harry Potter novel and, as Rowling noted, it "seemed too late" to introduce the character after that.[5] Rowling confirmed in a 2004 interview that Hermione is an only child.[6]

Rowling has described the character of Luna Lovegood as the "anti-Hermione" as they are so different.[7] Hermione's foil at Hogwarts is Pansy Parkinson, a bully based on real-life girls who teased the author during her school days.[8]