First pics of Alan Rickman as Ronald Reagan

Harry Potter star plays the former actor turned president in the all-star cast of The Butler

The first sighting of British actor Alan Rickman playing former president Ronald Reagan has emerged online.

Rickman is playing the actor-turned-head-of-state in forthcoming biopic 'The Butler', which tells the true story of Eugene Allen, a butler at the White House from 1952 to 1986.

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Allen is being played by Forest Whitaker, while his on-screen wife is being played by Oprah Winfrey, who posted the picture of Rickman on her Twitter page.

Rickman... as Reagan, with Jane Fonda as Nancy (Copyright: Twitter/@Oprah)

Rickman appears in the picture alongside Jane Fonda, who is portraying Reagan's wife Nancy.

She also posted a second picture of another of her co-stars, rock star Lenny Kravitz sporting greying hair and a tuxedo.

Kravitz... prematurely aged (Copyright: Twitter/@Oprah)

John Cusack and Robin Williams also star, Cusack playing Richard Nixon and Williams playing Eisenhower, while James Marsden takes on Kennedy and Liev Schreiber plays Lyndon Johnson.

Allen, who died in 2010 aged 90, served as a butler to eight American presidents in all and retired in 1986, having not missed a single day's work.