Quirrell is the professor for the defense against the dark arts at Hogwarts School of Witchcraft and Wizardry.
During the events of Harry Potter and the Sorcerer's Stone (2001) played by Ian Hart
Hagrid and Harry Potter go into the Leaky Cauldron and Hagrid introduces Harry to the Bartender in Leaky Cauldron and Professor Quirrell. Harry offers to shake Professor Quirrell's hand, however Professor Quirrell pulls back from Harry. At Halloween dinner during the school semester, Professor Quirrell runs into the Great Hall and yells there is a Troll in the dungeon. Professor McGonagall, Professor Snape and Professor Quirrell run into the bathroom and Hermione Granger takes the blame for being in the bathroom instead of somewhere safe and Gryffindor loses five points, but gains ten for Harry and Ron's bravery in defeating the Troll. During a Quidditch match, as Harry starts to go after the Snitch, his broom starts to act on its own. Hermione sees Snape mouthing spells and she starts a fire under Snape, who bumps into a professor who bumps into Professor Quirrell. Harry is able to regain control of his broom and catches the Snitch in his mouth and wins the game for Gryffindor. As he is trying to get away from the library, Harry sees Snape confront Professor Quirrell about his loyalty. Mr Filch shows Snape and Professor Quirrell the lantern he found in the restricted section. Later, Harry enters the last room beyond Fluffy and finds Professor Quirrell staring at the Mirror of Erised. Professor Quirrell tells Harry Snape was actually trying to save him during the Quidditch match and Snape knew he was up to something. Professor Quirrell wonders how to get the Sorcerer's Stone and a voice suggests he use Harry. Harry looks into the mirror and the mirror shows him the Sorcerer's Stone is in his pocket. Harry lies to Professor Quirrell about what he sees in the mirror and Professor Quirrell removes his headdress, revealing Voldemort's head living on the back of his skull. Professor Quirrell attacks Harry, but Harry manages to kill him when he notices that his touch wounds him and Harry causes Professor Quirrell to dissolve by touching him in the face.