American actor Paul Giamatti is joining the cast of the British award-winning stately home drama "Downton Abbey", starting with the Christmas episode, the show's producers said on Monday.
Carnival Films, a division of Comcast's NBCUniversal, and British television channel ITV said Giamatti would play Cora Crawley's maverick, playboy brother Harold in the Christmas episode.
Giamatti, known for films including "Sideways" and "Cinderella Man", will be star alongside Shirley MacLaine and the regular cast members in the drama that won a Golden Globe for Best Miniseries or Television Film in 2011.
He is just one of a list of new cast members to star in an eight-part fourth series that includes New Zealand opera singer Kiri Te Kanawa and follows the lives of the aristocratic Crawley family and their staff.
"We're excited that Paul Giamatti will be joining us on Downton to play Cora's brother Harold, the rather free-spirited uncle to Mary and Edith," Carnival Films' Managing Director Gareth Neame said in a statement.
"We can't wait to see him work alongside Shirley MacLaine, who are both sure to upset the Grantham's apple cart in this year's Christmas Day episode."
The new series will see the return of MacLaine as Martha Levinson alongside series regulars Hugh Bonneville, Maggie Smith, Michelle Dockery and Jim Carter.
In Britain, series three of "Downton Abbey" that was created by British screenwriter Julian Fellowes was the most watched drama of 2012, averaging 11.9 million viewers.
In the United States, shown on PBS, "Downton Abbey" was the highest-ranked non-U.S. series.