The actress has signed a contract to play the villain mother of Draco Malfoy, Narcissa, in Harry Potter and the Half-Blood Prince. The star will begin filming the sixth film of the series in September.
The star will join an essentially British cast, and said that she considers herself to be British. Watts said, "I consider myself British and have very happy memories of the UK. I spent the first 14 years of my life in England and never wanted to leave. When I was in Australia I went back to England a lot."
Harry Potter and the Half-Blood Prince will be directed by David Yates and should open in theatres in November of 2008.