Banshee

A Banshee is a reasonably rare demon with distinctive white hair, and a high pitched scream.

The Book of Shadows has an entry on Banshees, and a "To Track a Banshee" spell, which will turn the volunteer into a dog, which can hear the high-pitch cries of Banshees, outside of the human hearing range.

In 2001, Michelle was killed and returned as a Banshee to kill several people, including her husband. She was vanquished when Piper blew her up, but not before turning Phoebe into a Banshee as well. ("Look Who's Barking")