Luna Lovegood is a Ravenclaw student one year younger than Harry. She is described as having straggly waist-length dirty blond hair, grey eyes and a "permanently surprised look". Rowling has often said that Luna is the "anti-Hermione", as Hermione is "inflexible and logical", as opposed to Luna, who would "believe 10 impossible things before breakfast". Her father, Xenophilius Lovegood, is the editor-in-chief of The Quibbler. When Luna was only 9 years old, her mother died while performing spell experiments. Luna witnessed the accident, which enabled her to see Thestrals. Luna is at first socially isolated at school, but she appears to have the rare quality of caring little about what others think of her.
In Order of the Phoenix, she and her father are among the few who believe Harry and Dumbledore when they claim that Voldemort has returned, and even publish an article outlining Harry's side of events, as opposed to the ministry influenced media that try to portray Harry as crazy. During this particularly turbulent year for Harry, Luna is the only person who can quell his temper when Ron and Hermione cannot. As a result, he forms a strong friendship with her. Luna also becomes a member of Dumbledore's Army. Later in the book, she joins Harry, Ron, Hermione, Ginny, and Neville in the conflict with Death Eaters at the Department of Mysteries. In Half-Blood Prince, after Luna and Neville are snubbed by some of Harry's new fans, she observes that Harry is expected to be with "cooler" people. Harry later invites Luna to Slughorn's Christmas party. She also does the Quidditch commentary for Gryffindor's game against Hufflepuff, a scene that Rowling particularly enjoyed writing, calling it "blinding inspiration". Later, when Death Eaters attack Hogwarts, Luna, Ginny and Neville are the sole D.A. members who answer the call to protect Hogwarts.
In Deathly Hallows, Luna and her father attend Bill Weasley and Fleur Delacour's wedding at the Burrow, where she immediately recognises Harry (who is posing as another Weasley under the effects of Polyjuice Potion) by way of the expression on his face. She returns to school for her sixth year, where she and Neville help Ginny secretly revive the D.A. to oppose Snape's regime as Hogwarts headmaster. During Harry's visit to the Lovegood residence along with Ron and Hermione, the trio notices evidence suggesting that she has been missing for several weeks. It is then revealed that while travelling home for the Christmas break on the Hogwarts Express, Luna was kidnapped in an effort to prevent her father from publishing information in support of Harry. Harry, Ron, and Hermione, along with Luna, Dean Thomas, Griphook, and Mr Ollivander, are captured and held hostage at Malfoy Manor, but are soon rescued by Dobby, who takes them to safety at Shell Cottage. When Harry returns to Hogwarts in search of Ravenclaw's diadem, Luna helps him enter the Ravenclaw common room to view a replica of it, then stuns Alecto Carrow when they are discovered. During the battle, she, Ernie, and Seamus help Harry fight the Dementors by conjuring their respective Patronuses; Luna's takes the form of a silver hare. After Harry's apparent death, Luna ends up dueling Bellatrix Lestrange, along with Hermione and Ginny, until Molly Weasley takes over and defeats Bellatrix herself. She is among the first to congratulate Harry when Voldemort is defeated and later helps him get some solitude.
Rowling revealed that, after Hogwarts, Luna pursues a career that is "the wizarding equivalent" of a naturalist. She also accepted that some of her father's beliefs were, after all, not so true. She married a fellow naturalist named Rolf, the grandson of Newt Scamander. Luna and Rolf had twin boys, Lorcan and Lysander. After Harry and Ginny are married, they name their daughter Lily Luna.
Evanna Lynch portrayed Luna in the last four Harry Potter films.
IGN listed Luna as their 12th top Harry Potter character, saying that looniness made her a "delight". Empire listed Luna as their 10th favourite Harry Potter character in "The 25 Greatest Harry Potter Characters".