Severus Snape was the Potions Master, Head of Slytherin house, Defence Against the Dark Arts professor, and eventual Headmaster of Hogwarts School of Witchcraft and Wizardry. One of the most complex and pivotal characters in the series, Snape lived a double life as both a Death Eater loyal to Lord Voldemort and a member of the Order of the Phoenix secretly working for Albus Dumbledore. His actions were driven by a lifelong, unrequited love for Lily Evans, Harry Potter's mother. This profound motivation led him to play a crucial, albeit often cruel and misunderstood, role in protecting Harry and ensuring Voldemort's ultimate defeat.
Severus Snape was born to a witch, Eileen Prince, and a Muggle, Tobias Snape. He grew up in a neglectful household on Spinner's End, a shabby, derelict street. As a child, he met and befriended Lily Evans after recognizing that she, too, was magical. He fell deeply in love with her and was the first to explain the wizarding world to her.
At Hogwarts, Snape was sorted into Slytherin house. He proved to be a gifted student, particularly in Potions and the Dark Arts. He frequently experimented with and created his own spells, such as `Sectumsempra` and `Muffliato`, annotating his copy of Advanced Potion-Making with his discoveries under the moniker “The Half-Blood Prince”. Throughout his time at school, he was the target of relentless bullying by James Potter and Sirius Black. His friendship with Lily became strained due to his fascination with the Dark Arts and his friendship with aspiring Death Eaters. The friendship ended permanently after Snape called Lily a “Mudblood” in a moment of humiliation after being tormented by James Potter.
After graduating from Hogwarts, Snape joined the Death Eaters. While in their service, he overheard a portion of the Prophecy made by Sybill Trelawney regarding the one with the power to vanquish the Dark Lord. He relayed this information to Lord Voldemort, who interpreted it as referring to the son of Lily and James Potter. Horrified that he had endangered the woman he loved, Snape defected and went to Albus Dumbledore, begging him to protect the Potters. In exchange, Snape swore his allegiance to Dumbledore, becoming a double agent for the Order of the Phoenix. Following the Potters' deaths, a grief-stricken Snape was persuaded by Dumbledore to dedicate his life to protecting Harry Potter as a way to honor Lily's memory and sacrifice.
Dumbledore secured Snape a position as the Potions Master at Hogwarts, a role which protected him from being sent to Azkaban. For years, he coveted the post of Defence Against the Dark Arts professor but was consistently denied it. During Harry Potter's time at school, Snape was a harsh and biased teacher, showing clear favoritism towards Slytherin and a deep-seated animosity towards Harry, whom he saw as a living embodiment of his rival, James. Despite his personal disdain, he covertly protected Harry on numerous occasions, such as when he performed a counter-curse against Quirinus Quirrell's jinx during a Quidditch match in Harry's first year.
Upon Lord Voldemort's return, Snape resumed his role as a double agent on Dumbledore's orders, successfully convincing the Dark Lord of his continued loyalty. He made an Unbreakable Vow with Narcissa Malfoy to protect her son, Draco Malfoy, and to carry out the task Voldemort had assigned him—killing Albus Dumbledore—should Draco fail. This task was part of a secret pact between Snape and Dumbledore, who was already dying from a curse. Snape killed Dumbledore atop the Astronomy Tower, an act that solidified his standing within the Death Eaters' inner circle and allowed him to become Headmaster of Hogwarts. As Headmaster, he secretly worked to protect the students and aid Harry's quest, most notably by guiding Harry to the Sword of Gryffindor using his Patronus.
During the Battle of Hogwarts, Snape was summoned to the Shrieking Shack by Lord Voldemort. Mistakenly believing Snape to be the master of the Elder Wand, Voldemort ordered his snake, Nagini, to kill him, hoping to claim the wand's allegiance. As he lay dying, Snape gave his memories to Harry Potter. These memories revealed the entirety of his story: his love for Lily, his true allegiance to Dumbledore, and his role as a secret protector of Harry. In his final act, Snape ensured that Harry knew the truth about his destiny. Years later, Harry honored his memory by naming his second son Albus Severus Potter and describing Snape as one of the bravest men he ever knew.
Snape is described as a thin man with sallow skin, a large, hooked nose, and greasy, shoulder-length black hair. His eyes are black, cold, and “empty like dark tunnels.” He typically wore sweeping black robes, which made him resemble an “overgrown bat.” His personality was acerbic, sarcastic, and cruel, particularly towards students he disliked, such as Harry and Neville Longbottom. He was a man of immense self-control and profound bravery, capable of deceiving the most accomplished Legilimens in history for years. Beneath his bitter and resentful exterior lay a deep capacity for love, though it was focused entirely on the memory of Lily Evans. This duality made him one of the most morally ambiguous and tragic figures of the wizarding world.