When Harry Potter kicked off the ghosts were central to the appeal. Given a massive amount of screen-time relative to their actual importance to the plot, they were everywhere, with John Cleese even getting fourth highest billing (behind the three leads) on The Philosopher's Stone. As the series went by they played a less prominent role, but there was still one ghostly character who would prove essential in the story's finale; Helena Ravenclaw. The daughter of Rowena Ravenclaw, Helena helps Harry find her mother's diadem, one of Voldemort's last remaining horcruxes in The Deathly Hallows. In the film she's played by Kelly Macdonald, but originally the part of the Grey Lady was offered to Kate Winslet. A massive star even by Potter standards, Winslet never got a say on whether she'd take the role or not, with her agent rejecting the offer out a rather snobbish view on Potter's prolificness.
