Quirinus Quirrell's turban

"Petrified, he watched as Quirrell reached up and began to unwrap his turban. What was going on? The turban fell away. Quirrell's head looked strangely small without it. Then he turned slowly on the spot. Harry would have screamed, but he couldn't make a sound. Where there should have been a back to Quirrell's head, there was a face, the most terrible face Harry had ever seen. It was chalk white with glaring red eyes and slits for nostrils, like a snake."

This turban was used by Professor Quirinus Quirrell to hide the face of Lord Voldemort after the Dark Lord possessed him. He ued it after he failed to steal the Philosopher's Stone out Gringotts Wizarding Bank. Quirrell's story was that an African prince gave him the turban as a thank-you for getting rid of a troublesome zombie. Whether he only made up the turban part or the whole tale is unclear.

"Mere shadow and vapor. I have form only when I can share another's body, but there have always been those willing to let me into their hearts and minds. Unicorn blood has strengthened me, these past weeks. You saw faithful Quirrell drinking it for me in the Forest. And once I have the Elixir of Life, I will be able to create a body of my own"

- Lord Voldemort on Quirinus Quirrell's deeds

The turban would have only been used until Voldemort got the Elixir of Life and achieved a body of his own.

Behind the Scenes
In the film, Quirrell was wearing the turban at the Leaky Cauldron pub, when he first met Harry Potter.