Outward appearance
In the books, Hermione is described as having bushy brown hair, brown eyes, and large front teeth until Goblet of Fire, when she is hit by a spell cast by Draco Malfoy, that causes her teeth to grow uncontrollably until she has Madam Pomfrey magically shrink them to a size smaller than they were originally.

Personality
Hermione’s most prominent features include her prodigious intellect and cleverness. She is levelheaded, book-smart and is very good with logic, but at first, she has a tendency to panic in intense or scary situations (as with the Devil’s Snare at the climax of Philosopher’s Stone) and is not good at thinking on her feet. However, by Deathly Hallows, she has learned to be more instinctive, saving everyone’s lives more than once with her quick thinking. She is often bossy yet very loyal and conscientious. Rowling stated that Hermione is a person that “never strays off the path; she always keeps her attention focused on the job that must be done.” Despite Hermione’s intelligence and bossy attitude, Rowling says that Hermione has “quite a lot of vulnerability in her personality,” as well as a “sense of insecurity underneath,” feels “utterly inadequate…and to compensate, she tries to be the best at everything at school, projecting a false confidence that can irritate people.” During her Defence against the Dark Arts exam at the end of Harry Potter and the Prisoner of Azkaban, Hermione reveals that her biggest fear is failure, after a Boggart takes the form of Professor McGonagall and tells her that she has failed all her exams.

Hermione has an extremely compassionate side to her personality and is quick to help others, especially those who are defenceless, such as Neville Longbottom, first-years, House-Elves, fellow Muggle-borns, half-giants like Hagrid and werewolves like Lupin. It was revealed by Rowling after the publication of the final book that Hermione’s career in the Ministry was to fight for the rights of the oppressed (such as House-elves or Muggle-borns). Hermione is also very protective of her friends and values them so much that Rowling has suggested that, if Hermione had looked in the Mirror of Erised, she would have seen Harry, Ron, and herself “alive and unscathed, and Voldemort finished.”

Magical abilities
Hermione is portrayed during the whole series as an exceptionally talented young witch. Rowling has stated that Hermione is a “borderline genius.” She is the best student in Harry’s year, as she is repeatedly the first student to master any spell or charm introduced in classes and even from more advanced years, as evidenced when she is able to conjure a Protean Charm on the D.A.’s fake Galleon coins, which is actually a N.E.W.T. level charm. She is also the first one to be able to cast non-verbal spells. Hermione is an exceptional duellist, capable of outmatching even Death Eaters, as shown in the battle at the Department of Mysteries, at the Lovegoods’ house, and in the Battle of Hogwarts. However, Rowling has stated that while during the first three books Hermione would have beaten Harry in a magical duel, by the fourth book Harry is so good at Defence Against the Dark Arts that he would have defeated Hermione. Hermione did not tend to do as well in subjects that were not learned through books or formal training, as broom flying did not come as naturally to her in her first year as it did to Harry, and she showed no affinity for Divination, which she dropped from her third year studies. She was also not good at Wizard’s Chess, as it was the only thing at which she ever lost.

Hermione’s Patronus is an otter, Rowling’s favourite animal. Her wand is made of vine wood and dragon heartstring core; vine is the wood ascribed to Hermione’s fictional birth month (September) on the Celtic calendar.