The audience is introduced to many professors when Harry starts his schooling at Hogwarts. Their backstories play a significant role in the story.
Almost every character in the Harry Potter franchise has a detailed backstory. The professors at Hogwarts, in particular, have fascinating pasts. Professors at the School of Witchcraft and Wizardry teach subjects such as Potions, Transfiguration, and Defense Against The Dark Arts. But, there's more to these teachers than meets the eye.
Viewers learn about some of the professor's backstories in the movies. However, a few of the professor's pasts are only revealed in the books. Many of Hogwart's professors are mysterious, and their lives before they met Harry range from amusing to dangerous.
Cassandra Trelawney was a renowned Seer. For three generations, no one else besides Cassandra possessed her gift. However, her great-great-granddaughter Sybill began prophesying the future. But, none of her visions came to fruition. Sybill spent many years struggling to gain recognition as an actual Seer.
Dumbledore was looking for a new Divination professor. During his interview with Sybill, she made a prophecy concerning Voldemort and the chosen one. Despite only giving one accurate prediction, Dumbledore hired Sybill to protect her.
While many witches think Lockhart is a dreamboat, he's actually a big phony. He's professor of Defense Against the Dark Arts during Harry's second year but is exposed as a fraud.
Growing up, Lockhart had two squib siblings. Despite being his mother's favorite, he wasn't well-known at Hogwarts. He created a spell that shot a hologram of his face into the sky and sent himself 800 Valentines to gain attention. After graduation, Lockhart began erasing the minds of wizards and took credit for their accolades.
During Harry's first year at Hogwarts, Quirinus Quirrell is introduced as a nervous and stuttering professor. However, he is not the coward he pretends to be. He is a dedicated servant of Voldemort.
As a student, Quirrell developed an interest in the Dark Arts. He taught muggle studies after graduating but took a year off to gain more experience in the field. But, in reality, he was searching for Voldemort. Quirrell found Voldemort, and he attached himself to the back of his head.
Mad-Eye Moody wasn't technically a professor. Barty Crouch, Jr. kidnapped Moody before he arrived at Hogwarts. He disguised himself as Moody using Polyjuice Potion and taught Defense Against the Dark Arts using his identity.
Barty Jr. became a Death Eater in his teen years and tortured Neville Longbottom's parents. He was imprisoned in Azkaban but escaped with his mother's help. Barty Senior used the Imperius Curse to control his son. But, Voldemort freed Barty Jr., which led to the events of The Goblet of Fire.
Horace Slughorn was a professor of Potions during Harry's sixth year at Hogwarts. However, he was also the Potions Master in 1931-1981. He taught during the time Voldemort and Harry's parents were in school.
He formed an organization known as the "Slug Club," filled with well-connected or skilled students. He was fond of Lily. But, before that, he also liked Tom Riddle. Slughorn makes the mistake of giving him information on Horcruxes, which kept Voldemort alive for a long time.
The groundskeeper at Hogwarts during Harry's years at Hogwarts was Rubeus Hagrid. However, he also taught Care of Magical Creatures for a time. This surprised many due to his troubled past.
Hagrid, a half-giant, snuck many creatures into Hogwarts as a student. One of these creatures was Aragog, an Acromantula. Tom Riddle framed Aragog for murdering a student when it was actually the monster from the Chamber of Secrets. Hagrid was expelled despite Dumbledore’s insistence on his innocence, and his wand was broken.
The head of the Gryffindor house and the Transfiguration's professor, Minerva McGonagall, is a fan-favorite teacher. She's strict but fair. However, fans may be surprised to learn that the sensible McGonagall once fell head over heels for a muggle.
McGonagall achieved top marks at Hogwarts and got a job at the Ministry of Magic. But, she became engaged to the muggle Dougal McGregor one summer. McGonagall didn't want to lose her job, so she broke up with McGregor. She was brokenhearted but became a very successful witch.
The most hated professor, Severus Snape, teaches Potions and is head of the Slytherin house. He's harsh to his students, especially Harry. However, fans learn Snape's true intentions in the Deathly Hallows.
Snape was a childhood friend of Harry's mother, Lily. He loved her even after their falling out. After her death, Snape became a double agent. He served Voldemort as a Death Eater but leaked information to Dumbledore. The memory Snape gives to Harry before he dies plays a considerable role in Voldemort's defeat.
Remus Lupin was the Defense Against the Dark Arts professor during Harry's third year. Lupin helped Harry face Dementors and told him stories of his father. But, Lupin also hides many secrets from Harry.
Lupin was attacked by Greyback as a child, turning him into a werewolf. He struggled with his condition. However, his fellow Marauders (James Potter, Sirius Black, and Peter Pettigrew) became Animagus' to protect him and others at Hogwarts. They also all became members of the Order of the Phoenix after graduation.
Dumbledore's past is varied and complex. His younger sister, Ariana, was attacked by a group of muggles. It scarred her for life. So, Dumbledore became responsible for Ariana after his mother's death and his father's imprisonment.
After graduating, Dumbledore began a romance with Grindelwald. The two planned to start a revolution but got into a fight that killed Ariana. Dumbledore vowed never to seek power again. He became a Transfiguration professor and later the headmaster of Hogwarts. His backstory is the most mysterious and significant of them all.