Well, this is certainly unexpected. The TV landscape has changed in recent years in such a way that few would bat an eye at an A-list movie star making an appearance on a prominent cable series, but Paul Giamatti on PBS period drama 'Downton Abbey'? Now we've heard everything.

According to TVLine, Giamatti will first appear in the season 4 finale episode as Harold Levinson, a "maverick, playboy brother" to Cora (Elizabeth McGovern) and uncle to Mary (Michelle Dockery) and Edith (Laura Carmichael). 'Downton Abbey' Executive Producer Gareth Neame described Harold's character as “free-spirited,” and revealed that both Giamatti and returning guest star Shirley MacLaine will “upset the Grantham’s apple cart” in the finale. British!

Meanwhile, the fourth season of PBS' hit drama will premiere in the US on Jan. 14, featuring new guest stars Dame Harriet Walters as an old friend of Maggie Smith’s Dowager Countess, Nigle Harman as a visiting valet named Green, and Tom Cullen as Lady Mary's new love interest, following Dan Stevens' untimely exit from the series.

Well, what say you? Does the prospect of seeing the Rhino himself on 'Downton Abbey' endure you at all to the period drama's fourth season? What would you like to see when the new episodes premiere next January?

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