Harry Potter
Harry Potter, "The Boy Who Lived," the savior of the wizarding world and the only living wizard to defeat Lord Voldemort, is the protagonist of J. K. Rowlings series of novels. In this third installment, Harry heads back to Hogwarts with the threat of an escaped convict, Sirius Black, who according to the Ministry of Magic wants nothing more than to add Harry to his long list of alleged murder victims.
Ron Weasley
Ron is one of Harry's best friends and is his partner in crime. Ron comes from a huge wizarding family, the Weasleys. What they lack in wealth, they make up for in love and kindness. Ron's relationship with Harry is sometimes strained by the notion that he is merely a "sidekick," and he falls short of his friend's talent and athleticism on the quidditch field. But Ron is always loyal and courageous when he needs to be.
Hermione Granger
Hermione Granger is Hogwarts' cleverest pupil and Harry's other best friend. She learns spells easily and is always the first to solve problems and crack mysteries. Hermione's academic ambitions play a prominent role in this book, because she requires the use of a time-turner to take more classes than is possible in the normal constraints of time. Her time-turner serves a higher purpose at the end of the book when she and Harry go back in time to save innocent lives.
Remus "R.J." Lupin, aka Moony
Remus Lupin is the newly appointed teacher of Defense against the Dark Arts at Hogwarts. He quickly becomes a favorite teacher among students for his "hands-on" approach, teaching the students to cast spells instead of having them use their textbooks. Since he was a boy, Lupin has suffered from being a werewolf. He was best friends with Harry's dad at Hogwarts, and together with James Potter, Sirius Black, and Peter Pettigrew, created the Marauder's Map.
Sirius Black
Sirius Black is the titular prisoner of Azkaban who is wrongly accused and convicted of causing Peter Pettigrew's death and the death of thirteen Muggles. Harry learns over the course of the novel that Sirius Black was his father's childhood best friend, the best man at his parent's wedding, and his own godfather. Sirius is also an Animagus and is able to transform into a black dog at will.
The Dursleys
Uncle Vernon, Aunt Petunia, and Harry's cousin Dudley make up the Dursleys of Number 4 Privet Drive. The Dursleys are Harry's only living relatives, and they are Muggles who hate everything having to do with magic and forbid Harry from talking about the wizarding world. Harry's life with the Dursley's is miserable, but he's forced to live there every summer. Uncle Vernon is a beefy drill salesman, Aunt Petunia is a stay-at-home gossip, and Dudley is a spoiled, gluttonous teenager who enjoys nothing more than watching his dad verbally abuse Harry.
Aunt Marge
Marge is Vernon's sister who visits the Dursley's at their house for a few weeks at the end of summer. She breeds English Bulldogs and harbors a particularly passionate hatred for Harry. She takes her inexplicable feelings toward him a step too far one evening by insulting Harry's parents; in his rage, he accidentally inflates Marge like a balloon.
Mr. and Mrs. Weasley
Arthur and Molly Weasley are the parents of the Weasley clan. They are both loving and they dote upon Harry and their children, but they have different ideas of what the children can handle. Arthur works at the Ministry of Magic and believes that Harry must be informed about the danger he faces with Sirius Black on the loose, but Molly thinks Harry is just a boy, and need not be worried with the adult realities of his situation.
Rubeus Hagrid
Hagrid is the gameskeeper at Hogwarts and a personal friend of Harry, Ron, and Hermione's. He has a bit of an unhealthy obsession with dangerous magical creatures, but this year he finally has an outlet for his obsession when he is appointed professor to teach Care of Magical Creatures.
Albus Dumbledore
The impish, seemingly all-knowing Headmaster of Hogwarts. Dumbledore is beyond upset by the fact that Dementors are patrolling the grounds of his school, but he recognizes that they are a necessary evil to maintain the safety of his pupils.
Draco Malfoy
Draco Malfoy is a third-year Slytherin and Harry's schoolyard nemesis throughout the series. In this installment, Draco makes a problem for Hagrid when he rudely approaches Hagrid pet hippogriff, Buckbeak. Buckbeak slashes Malfoy's arm with his talon and is consequently sentenced to execution.
Sybill Trelawney
Trelawney is the professor of Divination at Hogwarts. She teaches students the imprecise art of seeing the future, reading palms and tea leaves, and gazing into crystal balls. The narration suggests strongly that Trelawney lacks the "inner eye" until the end, when she appears to have a real prophecy. The catch is that she doesn't actually remember having the prophecy.
Peter Pettigrew
Peter Pettigrew was a childhood friend of James Potter, Lupin, and Sirius Black. He is an Animagus and can turn into a rat at will. The particular rat he turns into happened to fall into the hands of the Weasleys twelve years ago, after he framed Sirius for selling the Potters out to Voldemort and killing thirteen Muggles.
