Quirinus Quirrell, Was the First Defence against the dark arts teacher Harry had ever had, He was also reveleaded to be guilty of having Voldemort on the back of his head, This was only because Quirrell Had failed to collect the stone from vault 317.

So Voldemort thought he should keep a closer eye on him by attaching to his body, Forcing Quirrell to wear the turban to hide him.

on Halloween of 1991, Quirrell Informed the school that there was a troll in the dungeons, Which he had at the present time, Let in.

It is obvious, Of course, That when Quirrell was a student at Hogwarts school of witch craft and wizardy, He was sorted into slytherin House.

Quirrell's Last stand was in the dungeons with Harry, With the mirror of erise, Trying to get the stone off him after the mirror had put it in his pocket.

After that Quirrell Tried to Kill Harry by strangling him, but the power of love stopped him in his tracks and he crumpled.

Quirinus Quirrell: What is this magic?