In Harry Potter and the Sorcerer's Stone, Harry Potter, the protagonist of the series, learns he is a wizard at age 11. He goes off to school at Hogwarts School of Witchcraft and Wizardry, learning along the way his name is famous. He is known as the "boy who lived"—the child who managed to survive the killing curse of the Dark Lord Voldemort (who murdered his parents) and somehow helped cause the Dark Lord to disappear. As Harry learns how to practice magic and get along at a new school, he must also come to terms with his new identity as a hero and celebrity. Harry soon learns Voldemort is not dead but simply disembodied. What's more, the Dark Lord is making every effort to regain his body and his power. A key to this effort is discovering just why the killing curse failed to kill young Harry, so Harry finds himself pursued by Voldemort with increasingly murderous intent. Harry's journey from neglected orphan to true hero is one of growth and self-discovery. As he learns more about his parents' deaths and must repeatedly confront Voldemort, he becomes stronger both in magic and in understanding. In the end he must make the ultimate choice: sacrifice his own life or attempt to preserve it.
Muggle (human)-born Hermione Granger is the daughter of two dentists and so, like Harry, does not learn she is a witch until she is invited to Hogwarts on her 11th birthday. She immediately begins reading up on the subject and manages to arrive at Hogwarts already having extensive knowledge of its history. She is a conscientious and hardworking student who excels in every class and is seen as a know-it-all. She becomes friends with Harry and Ron after the three work together to defeat a troll in Harry Potter and the Sorcerer's Stone. Hermione is the smartest member of the trio and also the most well-read. In fact, she turns first to the library in any crisis and even brings several books along when the three must go into hiding in Harry Potter and the Deathly Hallows. Her levelheadedness is an important balance for Harry's impulsiveness. Hermione is annoyed at Ron for significant periods of time throughout the series but eventually falls in love with him.
Ron (Ronald) Weasley becomes Harry's first friend at Hogwarts after they meet in Harry Potter and the Sorcerer's Stone. He has a background as far from Harry's as possible. While Harry is an orphan living with his neglectful aunt and uncle, Ron is from a large and loving family. While Harry knows nothing of the magical world, Ron has grown up in a family where doing tasks magically is the norm. His older brothers all attend or have attended Hogwarts, and his father works for the Ministry of Magic. Ron's background makes him take his place in society for granted. He is insensitive to the struggles of Harry and Hermione, who, coming from Muggle homes, are less comfortable at Hogwarts and feel more pressure to be accepted there. He does not understand why Hermione is so angry about the enslavement of house-elves because, to him, it is the norm. However, being one of many siblings has its disadvantages. He is often overshadowed by his older brothers, who excel in academics or in Quidditch (a ball game played in the air), have glamorous jobs, or are budding entrepreneurs. Being overshadowed is part of being best friends with a celebrity such as Harry Potter. Part of Ron's journey is learning to accept he will never be as famous as Harry and finding he does have something to offer despite this lack of fame. He eventually finds peace with himself, fights bravely against Voldemort, and falls in love with Hermione.
Albus Dumbledore is already an accomplished and powerful wizard by the time Harry meets him in Harry Potter and the Sorcerer's Stone. He is not just headmaster of Hogwarts but something of a celebrity himself. His chocolate frog card (similar to a trading card) states he is "considered by many the greatest wizard of modern times," and is famous for "his defeat of the Dark wizard Grindelwald in 1945, for the discovery of the twelve uses of dragon's blood, and his work on alchemy with his partner, Nicolas Flamel." Dumbledore is a wise, guiding presence throughout the series. He explains to Harry many of life's most important lessons, encourages him, and protects him in every way possible. However, for several years, Dumbledore keeps an important secret from Harry: the prophecy that caused Voldemort to seek out Harry and try to kill him. He has other secrets, too, both about his own past and about Voldemort. He begins to reveal these secrets to Harry in Harry Potter and the Half-Blood Prince but is killed before he shares all he knows. Dumbledore reappears from beyond the grave at a critical moment at the climax of the series and helps Harry face his final task.
First appearing in Harry Potter and the Sorcerer's Stone, Voldemort, the Dark Lord, was born Tom Marvolo Riddle—the son of Merope Marvolo, a witch, and Tom Riddle, a Muggle. Orphaned at a young age and raised in an orphanage, he went on to become one of the most powerful dark wizards of all time. When he learns of a prophecy about one who has the power to "vanquish the Dark Lord," he immediately sets out to identify and kill this person. He decides the one he must eliminate is Harry Potter, then only 15 months old. However, the killing curse he casts at Harry rebounds because of the protective magic of Harry's mother, who gives her life to save her son. Voldemort's driving ambition is to achieve victory over death and absolute rule over all others. He creates Horcruxes to foil death, and he recruits Death Eaters, loyal followers who set up a reign of terror. He is ultimately undone by his inability to understand love and self-sacrifice.
When Harry Potter begins his education at Hogwarts in Harry Potter and the Sorcerer's Stone, Potions teacher Severus Snape has clear disdain for the young wizard. This outright antagonism leads Harry to believe Snape is behind attempts to hurt him and to steal the Sorcerer's Stone. Although Snape turns out to have been working with Dumbledore to protect the stone, Harry carries this suspicious attitude toward Snape throughout the series. Despite Dumbledore's assurances Snape is trustworthy, Harry doesn't fully believe it until after Snape is killed, and Harry learns his story in full. Since readers see Snape from Harry's perspective in the series, they are also kept in the dark about his motives and role in Dumbledore's efforts to oppose Voldemort. When Snape kills Dumbledore and joins Voldemort's Death Eaters, his true loyalty remains unclear. Little by little, the series reveals the story behind Snape's behavior and the reason he both dislikes Harry and risks his own life to save him—love.
As one of James Potter's closest school friends, Sirius Black was chosen to be "Secret-Keeper" for the Potters when word came Voldemort had targeted them. As Secret-Keeper, he would be the only one able to divulge the location of the Potters. At the last minute, however, Sirius suggested Peter Pettigrew be Secret-Keeper. Pettigrew went on to betray the Potters' location to Voldemort while Sirius Black went to prison. He was widely believed to have betrayed Harry's parents and to have murdered several Muggles in his attempt to avoid capture. When he escapes from prison in Harry Potter and the Prisoner of Azkaban, he is slightly mad having spent many years in Azkaban, and he is on a mission of revenge: find Peter Pettigrew and kill him. Harry, at first believing Sirius betrayed his parents, eventually learns the truth and saves Sirius from capture. Over the next book, Sirius is on the run, as he is still considered guilty by the authorities. By Harry Potter and the Order of the Phoenix, Sirius is a member of the Order and his ancestral home is its headquarters. However, because he is still a wanted man, he must stay inside the house. This predicament is psychologically difficult for an already emotionally compromised man, as his pure-blood family is almost entirely made up of Death Eaters who have rejected him as a "blood traitor." Sirius emerges from hiding just in time to fight Death Eaters in the Department of Mysteries, and he is killed while fighting his Death Eater cousin, Bellatrix Lestrange.