Here's who's who in Rowling's saga

Here's a primer on the people and places in Harry Potter's world:
HARRY POTTER
As a baby, Harry was orphaned when the evil Lord Voldemort killed his wizard parents, James and Lily Potter. Harry was left with a lightning-shaped scar on his forehead that marks him as a hero in the wizarding world. However, until he was 11, Harry lived with his nonwizard Aunt Petunia and Uncle Vernon Dursley, who dote on their son Dudley and loathe their nephew.
On his 11th birthday, Harry learns that he is a wizard and starts his studies at the Hogwarts School of Witchcraft and Wizardry. Over the course of the first five books, Harry becomes adept at magic and succeeds at thwarting Voldemort's regular efforts to kill him. Harry also learns that he eventually must have a final showdown with Voldemort to fulfill the prophecy that links them: "Neither can live, while the other survives."
LORD VOLDEMORT
The head evildoer in the wizard world, Lord Voldemort murdered Harry's parents in his quest to defeat the forces of good. Voldemort, whose name in French means "flight of death," is so frightening to most wizards that they dare only refer to him as "You Know Who" or "He Who Must Not Be Named."
Voldemort nearly died when his effort to kill baby Harry reverberated on him. Over the course of the first five books, however, Voldemort's followers help him regain his strength and power.
HOGWARTS
The school offers a seven-year course in such basics as Potions, Transfiguration, Magical Theory, Defense Against the Dark Arts and Spells. Students are sorted into one of four houses when they first arrive; the houses vie with each other for various prizes during the school year.
RON WEASLEY and HERMIONE GRANGER
These are Harry's best friends, who put up with his sometimes unpredictable moods and stick with him through times of danger. Ron, red-haired and freckle-faced, offers Harry courage and loyalty. He is one of several children of Arthur and Molly Weasley, a venerable wizarding family that can be expected to help lead the charge against Voldemort.
Hermione can be rather bossy and too academically oriented, but her intelligence and cool head are some of the most potent weapons in Harry's battle against Voldemort.
DRACO MALFOY
Smooth and cruel, Draco is Harry's enemy at Hogwarts. The son of a wizard who has been a close aide to Voldemort, Malfoy is jealous of Harry's status as a wizard legend and constantly tries to make trouble for him.
RUBEUS HAGRID
Enormous in size and a little too fond of strong drink, Hagrid is the groundskeeper at Hogwarts. He also teaches the Care of Magical Creatures courses, and is a friend to all animals -- especially dangerous ones. Hagrid watches out for Harry, and has developed a close friendship with Ron and Hermione.
ALBUS DUMBLEDORE
The head of Hogwarts, he is legendary for his wizard powers. For Harry's first years at Hogwarts, Dumbledore tries to protect him from the fate that awaits him. In Book Five, however, Dumbledore finally realizes that he must tell Harry the truth -- that either he or Voldemort must die in the battle of good vs. evil.
SEVERUS SNAPE
Snape, the malevolent, sharp-tongued Potions master at Hogwarts, was once one of Voldemort's followers and still has a "dark mark" -- the branding symbol that allows the evil Lord to call his minions together. Dumbledore trusts Snape and believes he is a valuable member of the forces of good, but Harry and his friends distrust him, especially because he singles out Harry for unfairly harsh treatment.
GINNY WEASLEY
Younger sister to Ron, Ginny has lost much of her initial shyness around Harry. Once used as an unwitting pawn by Voldemort, Ginny is ready to join the fight against him.
MUGGLES
Humans who aren't born with wizarding genes. Harry's aunt and uncle are muggles, as are Hermione's parents.
QUIDDITCH
A wizard game, played on flying broomsticks. Quidditch is a wildly exciting, cricket-type game that is an obsession with many in the wizarding world, including Harry and Ron.