Quirinus Quirrell

"No dear boy. I tried to kill you. And trust me. If Snape's cloak hadn't caught fire and broken my eye contact I would have succeeded. Even with Snape muttering his little counter curse."

- Professor Quirrell revealing his true colors.

"Quirrell: Master, you are not strong enough. Voldemort: I have strength enough for this."

- Quirrell and Voldemort, before Quirrell removes his turban

Professor Quirinus Quirrell is the hidden main antagonist in the first Harry Potter book and movie, Harry Potter and The Philosopher's Stone as revealed during the climax.

He was a wizard and a Defense Against the Dark Arts teacher during Harry Potter's first year at Hogwarts. Although Severus Snape was initially thought to be the one trying to steal the Philosopher's Stone, it is ultimately revealed that the real villain is Quirrell.

He is portrayed by Ian Hart, who also does the voice of Voldemort in the same film.

Appearance
Quirrell was a young man with light blue eyes and very pale skin.

When Quirrell returned from his sabbatical in Albania, one of his eyes developed a twitch and his skin became quite pale. At the start of the term, he wore a purple turban.

Near the end of his life, it was revealed under his turban that he had allowed Voldemort's fledging body to grow a face at the back of his own head and joined forces with him.

History
Quirrell was once an insecure and stuttering man, his face twitching constantly. When he was a student at Hogwarts, he was sorted into Ravenclaw house. J.K. Rowling stated that he was teaching Muggle Studies before taking over Defense Against the Dark Arts. He traveled around the world to get subject for his lessons and during one of these travels, he met the disembodied Lord Voldemort, who gained him to his cause. From then on, the shy, young teacher would become much more confident and ruthless, though he kept acting like his old self as a facade.

When Harry and Hagrid are about to visit Diagon Alley to buy Harry's equipment for Hogwarts they enter the Leaking Cauldron. In the Leaking Cauldron, Harry is recognized by many witches and wizards, who are delighted to see the Boy Who Lived and want to shake his hand. There, Hagrid introduces Harry to Quirrell. After a short conversation, in which Harry notices Quirrell's distinctive stutter, Quirrell leaves them and Harry and Hagrid enter Diagon Alley.

Unbeknownst to Harry and Hagrid Quirrell breaks into Gringotts, the Wizards Bank, the same day and fails to steal the Philosophers Stone, as the vault was emptied by Hagrid only hours before. This leads Voldemort to the decision that he needs to watch Quirrell more closely and he possesses Quirrell's body. To hide Voldemort's face, which is now growing out of the back of his head, Quirrell wears a turban. Students, including Harry, recognize the foul smell but, as Quirrell claimed to have a backstory with a vampire, believe that the turban is simply filled with garlic.

When the Philosopher's stone is hidden at Hogwarts many teachers are asked by Dumbledore to help protect it, including Quirrel. Quirrell, who has a hand with trolls, dispatches one especially nasty specimen to guard the stone. As no teacher knows what spells protect the stone except their own, this goes unnoticed.

At Hogwarts, Quirrell does not act until Halloween, where he unleashes a troll in Hogwarts to cause a distraction. Planning to steal the Philosopher's Stone while the rest of the teachers are dealing with the troll, Quirrell is instead stopped when Snape, who grew suspicious, arrives first to stop anyone trying to steal the stone. However, the Cerberus Fluffy, one of the Stone's guardians, bites Snape and injures his leg. Both teachers catch up with the rest of the staff when they arrive to see that Ron Weasly and Harry Potter defeated the troll. There, Quirrell stays behind with the unconscious troll until the beast groans, prompting Quirrell to flee as well.

During the first Quidditch match of the season Quirrell bewitches Harry's broom, causing it to buckle and to try to throw Harry off to his death. However, as Snape is casting a counter spell Quirrell fails. When Hermione Granger, believing that Snape is the one who is trying to kill Harry, sets fire to Snape's robes to distract him, Snape knocks Quirrell over while trying to put out the flames and thereby disrupts Quirrell's concentration. In the book, Hermione accidentally knocks over Quirrell in her hurry to reach Snape.

While trying to find out who Nicholas Flamel is, Harry sneaks into the Restricted Section of the Hogwarts library, disguised by his invisibility cloak. On his way back, he meets Snape who is facing Quirrel over the attack at the Quidditch field, however from Harry's point of view it seems as Snape is trying to intimidate Quirrell. Sensing that someone is near, Snape stops intimidating Quirrell, instead telling him that they will have a little chat soon enough when Quirrell had enough time to decide where his loyalties lie. Filch then appears, telling them that he found Harry's lamp in the library. The two teachers and Filch then go to search for students sneaking around.

With Voldemort sharing a body with him, Quirrell needs to drink unicorn's blood for his master to survive. While in the Forbidden Woods drinking the blood of a unicorn he killed, Quirrell is disturbed by Harry and Draco Malfoy who were sent there for detention. Malfoy runs off screaming, but Harry's scar hurts so much due to being so close to Voldemort. Quirrell advances on Harry, but before he can harm him he is stopped by the centaur Firenze, who brings Harry to safety. After saving him, Firenze tells Harry that unicorn's blood keeps the one who drinks it alive, also telling Harry that the person he saw was no other than Voldemort himself.

To be able to steal the stone in peace, Quirrell forges a letter for Dumbledore, stating that he is needed in the Ministry of Magic. After Dumbledore has left Hogwarts, Quirrell advanced, passing every trial until the last. Meanwhile Harry, Ron and Hermione, thinking that Snape is trying to steal the stone to use its powers and bring Voldemort back to health, decide that they will go after the stone themselves. After braving many tests, Harry, separated from Ron and Hermione is forced to enter the last room alone but to his horror he is not awaited by Snape or Voldemort but by Quirrell.

Quirrell immobilizes Harry and then again faces the single object in the room, the Mirror of Erised. Though he sees himself handing the stone to his master Voldemort, but has no idea how to acquire it. Dumbledore later reveals to Harry that only those who would want to find the stone would be able to get it, not the ones whose desire was it to use the stone, as they would only see themselves drinking Elixir or making gold. Quirrell, now dropping the stuttering, weak facade, reveals to Harry how he was behind everything bad that had befallen Harry the last year, including bewitching his broom. Thereby he reveals to Harry that Snape was not trying to kill him but was effectively saving his life with a counter curse. Turning back to the mirror, Quirrell wonders how to get the Stone. At this point Voldemort, for Harry only a disembodied voice, tells Quirrell to "use the boy".

Quirrell tells Harry to stand before the mirror and tell him what he sees. Harry, who sees himself putting the Philosopher's stone in his pocket, realizes that the stone now is in his pocket and tries to deceive Quirrell by telling him that he sees that he has just won the house cup. Voldemort however is not so easily fooled and demands that Quirrell let him speak to Harry face to face. Though Quirrell initially claims that Voldemort is not strong enough yet, he removes his turban and reveals Voldemort's face to Harry. Voldemort, knowing that the stone is in Harry's pocket, demands that Harry turns it over but Harry tries to escape instead. With a snip of his finger, Quirrell conjures a burst of fire between Harry and the door, blocking the only way out. After Harry refuses to join Voldemort, Voldemort orders Quirrell to kill him. Quirrell tries to strangle Harry, but to the surprise of everyone his hands blister and crumble the very moment he touches Harry. In the movie, Harry kills Quirrell by pressing both hands on the professor's head, causing him to crumble into pieces.

In the books, Quirrell tries to kill Harry despite the pain and is stopped by Dumbledore, who wrestles Quirrell off Harry's body, the later having become unconscious. When Voldemort leaves the mortally wounded body of his fallen servant, Quirrell dies.

After Harry reawakens in the Hospital Wing of Hogwarts, Dumbledore explains to him that Quirrell was unable to touch him because when Harry's mother died for him, she created a powerful protection by her sacrifice. As Harry was protected by pure love, Quirrell, who was ambitious, evil and cruel was unable to touch him without suffering great pain.

Trivia

 * J.K. Rowling stated that Quirrell was partly an Horcrux, because he was holding a piece of Voldemort's soul inside him. So, it can be said that Quirrell was the first Horcrux that Harry destroyed instead of Tom Riddle's Diary. However, considering the story's logic, Quirrell cannot be one, since Horcruxes hold the parts of a wizard's soul that aren't with its conscience, and the one with Quirrell was the soul part which was Voldemort himself, soul and conscience. So when Harry touched Voldemort's bodily Horcrux, Quirrell ceased to exist.
 * In the movie, Quirrell has no part in the protection of the Philosopher's Stone. The part with the knocked out troll is missing.
 * In the books Harry is able to shake Quirrell's hand at the Leaky Cauldron as Quirrell was not sharing his body with Voldemort yet. However, in the movie Quirrell already wears his turban and therefore refuses to shake Harry's hand.
 * Archive footage of Quirrell sitting next to Snape in Harry Potter and the Philosopher's Stone is used in Harry Potter and the Deathly Hallows: Part 2. This footage continues with Quirrell turning into black smoke and disappearing to create the effects that this scene is a memory of Snape.
 * The name "Quirinus" is possibly derived from the Sabine word quiris meaning "spear". Quirinus was a Sabine and Roman god who was later identified with Mars. The name was also borne by several early saints.
 * Professor Quirrell was the second-to-final boss in the Gameboy color adaptation of Harry Potter and the Sorcerer's stone.
 * ​He is also the only boss who can use level 3 magic (tria magic).
 * In Jimmy Neutron Carl played a character based off of Quirrell and Tom Riddle from the Chamber of Secrets (with the former being a vessel for Voldemort and the later being an Incarnation of Voldemort).
 * He bears a resemblance to Judge Claude Frollo from Disney's Hunchback of Notre Dame.