Talk show queen Oprah Winfrey has joined the cast of Martin Luther King Jr. biopic `Selma`.

Winfrey is producing the film alongside Brad Pitt and now she is set to portray civil rights protester Annie Lee Cooper, an elderly woman who tried to register to vote and was denied by a sheriff, reports contactmusic.com.

The movie will reunite the 60-year-old with her Lee Daniels' `The Butler` co-star David Oyelowo, who will play King, while Cuba Gooding Jr. will star as American civil rights lawyer Fred Gray.

British actor Tom Wilkinson has signed on to play former US President Lyndon B. Johnson, and Tim Roth will portray controversial US governor George Wallace.