Harry James Potter is an English half-blood wizard, and one of the most famous wizards of modern times. Harry's birth was overshadowed by a prophecy, naming him as the one with the power to vanquish Lord Voldemort, the most powerful and feared dark wizard in the world. Harry became known as "The Boy Who Lived", when an attempt on his life, by Lord Voldemort failed and took his parents James and Lily Potter. Harry become orphaned at the death of his parents, and was rasied by Lily's only remaining blood relative and muggle aunt, Petunia Dursley and her husband. Protected by a powerful charm Albus Dumbledore cast upon him, Harry would not encounter Lord Voldemort until he came of age or no longer stayed with his Aunt Petunia and you can read about him here.
Hermione Jean Granger is an English muggle-born witch. At the age of eleven, she learned about her magical nature and was accepted into Hogwarts School of Witchcraft and Wizardry. She possessed a brilliant academic mind and proved to be a gifted student in almost every subject that she studied, to the point where she was nearly made a Ravenclaw by the Sorting Hat. Hermione first met future best friends Harry Potter and Ron Weasley on the Hogwarts express, and initially they found her to be unfriendly and a know-it-all. However, this changed when the boys saved her from a troll attack at the school and you can read more about her here.
Ronald Bilius Weasley is an English pure-blood wizard, and the 6th and youngest son of Arthur and Molly Weasley. Once arriving at Hogwarts School of Witchcraft and Wizardry, he became friends with Harry Potter and Hermione Granger, together making the golden trio facing many challenges through their adolescence. Including, keeping the Sorcerer's Stone from Professor Quirrell, rescuing Ginny Weasley from the Basilisk of the Chamber of Secrets, saving Harry's godfather Sirus Black from the Dementors and Azkaban, and guiding Harry through the Triwizard Tournament. Ron is the younger brother of Bill, Charlie, Percy, twins Fred and George, and is the older brother to Ginny Wealsey. Read more about him here.
Professor Albus Percival Wulfric Brian Dumbledore is an English half-blood wizard. He was the professor of Defense Against the Dark Arts, and later of Transfiguration, eventually becoming the Headmaster of Hogwarts School of Witchcraft and Wizardry. He was considered to have been the greatest wizard of modern times, perhaps of all time. Following the global wizarding war, Dumbledore became most famous for defeating Grindelwald in arguably the most epic battle of all time. He also gained much more recognition with his involvement in the discovery of the twelve uses of dragon's blood and his work on alchemy with Nicolas Flamel. Due to the fact that he had a keen mind and was a legendary figure, Dumbledore became the only wizard that Voldemort ever feared and you can read more about him here.
Professor Severus Snape is an English half-blood wizard serving as the Potions Master and Head of Slytherin House. He was also the Defence Against the Dark Arts professor, and a Death Eater. His double life played an extremely important role in both of the Wizarding Wars against Lord Voldemort. Severus was raised in a muggle dwelling where he met Lily and Petunia Evans, falling deeply in love and becoming close friends with Lily. While starting Hogwarts, Severus was sorted in Slytherin House while Lily was sorted in Gryffindor, his rival house. He immediately became the enemy of James Potter and Sirius Black, leading him to be irritable towards James's son, Harry Potter, when he become professor. When Severus was younger he developed a passion for Dark Arts and you can read more about him here.