Brad Pitt Joins George Clooney in Dustin Lance Black's Prop 8 Play

Brad Pitt is set to make history -- on stage.

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The Moneyball star will take on the role of United States District Chief Judge Vaughn R. Walker in Saturday's Los Angeles staging of Dustin Lance Black's play 8. Walker overturned California's gay marriage ban, ruling that Proposition 8 was unconstitutional after a highly publicized trial in July and August 2010.

The performance, which will take place at the Wilshire Ebell Theatre and serve as a fundraiser for gay marriage efforts across the country, boasts a star-studded cast. George Clooney and Martin Sheen will play the plaintiffs’ lead co-counsel David Boies and Theodore B. Olson, an unlikely pairing of a liberal and conservative lawyer working on behalf of marriage equality.

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Christine Lahti and Jamie Lee Curtis will take on the roles of Kris Perry and Sandy Stier, and Matthew Morrison and Matt Bomer will play Paul Katami and Jeff Zarrillo, two gay couples that put forth the law suit.

Jane Lynch will play anti-gay marriage activist Maggie Gallagher, co-founder of the National Organization for Marriage, while Kevin Bacon will portray the lawyer defending Proposition 8, Charles J. Cooper. John C. Reilly, who was once slated to play Walker, will play marriage equality advocate David Blankenhorn, founder and president of the Institute for American Values. Rob Reiner will direct.

Pitt has long been an advocate of marriage equality, and has until recently held firm to his statement that he and partner Angelina Jolie will not marry until everyone can do so.

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As he told The Hollywood Reporter, he and Jolie may end up tying the knot before that national dream is realized, but he is still open about his commitment to the cause of equality.

"To be in love with someone and be raising a family with someone and want to make that commitment and not be able to is ludicrous, just ludicrous," he said.