Item from harry-potter-order-of-the-phoenix by
Harry's father's cloak -- one of the three Deathly Hallows, though Harry doesn't know that yet. This year it's essential for DA meetings, midnight wanderings, and avoiding Umbridge's patrols.
The Invisibility Cloak is Harry's most practical inheritance and his most constant companion in subterfuge. This year he uses it to sneak to DA meetings, avoid the Inquisitorial Squad, visit Hagrid after hours, and generally move through a Hogwarts that has become hostile territory. Umbridge can't see through it -- neither can Filch or Mrs Norris, though both suspect invisible students more than they used to. The cloak was James Potter's before him, and before James it belonged to his father, and before that to his father's father -- an unbroken chain going back centuries, because this is no ordinary invisibility cloak. It is one of the Deathly Hallows, given by Death himself according to legend. Harry doesn't know this yet. He just knows it keeps him safe.
A shimmering, silvery cloak that flows like water and renders the wearer completely invisible. Light enough to fold into a pocket. Never wears out, never fades -- unlike ordinary invisibility cloaks, which degrade over time. There is something about it that feels different from regular magic, though Harry has never stopped to wonder why.
Also known as: the Invisibility Cloak, the cloak, Dad's cloak