Oscar-winning US actress Shirley MacLaine is to join the cast of Downton Abbey for its third series as the mother of Lady Grantham.
MacLaine - whose character is named Martha Levinson - will begin filming with the rest of the cast next month.
"It is so exciting to have an actress of Shirley MacLaine's stature joining our brilliant Downton Abbey cast," said Laura Mackie, ITV's director of drama.
"It is a tribute to the show's success on both sides of the Atlantic."
"Julian [Fellowes] has written another brilliant character in Martha Levinson, who will be a wonderful combatant for Maggie Smith's Dowager Countess," said Gareth Neame of Downton producer Carnival Films.
MacLaine has starred in more than 50 movies during her career and won an Oscar in 1984 for Terms of Endearment.
She has been nominated for a further five Academy Awards and recently received France's most prestigious cultural award, the Legion of Honour.
Her first film appearance was in Alfred Hitchcock's The Trouble With Harry, which earned her a Golden Globe award for most promising female newcomer in 1955.
Her other credits include The Children's Hour opposite Audrey Hepburn, The Apartment with Jack Lemmon, Steel Magnolias and Postcards from the Edge.
Downton Abbey recently won the National TV Award for best drama and a Golden Globe for best mini-series.
MacLaine will play the mother of Elizabeth McGovern's character, the American-born wife of Hugh Bonneville's Earl of Grantham.