See Daniel Radcliffe, Emma Watson, Ralph Fiennes in stills from the final Potter film
Helen McCrory as Narcissa Malfoy
The Death Eater Narcissa Malfoy (even her name sounds sinister) is played by Helen McCrory
She's the wife of Lucius Malfoy (Jason Isaacs) and the mother of Harry's school rival Draco (Tom Felton).
The Malfoys: A family of jerks.