The Hollywood star produced the Steve MCQueen film, about a free black man from New York who is abducted and sold into slavery, and makes a brief appearance onscreen as a Canadian abolitionist.
However, Pitt has played down the role he had in turning the real life story of Solomon Northup into a critically-acclaimed movie, which has already created Oscar buzz, insisting his main castmembers deserve all of the attention.
He tells U.S. breakfast show Today, "I'm there (onscreen) to support the story. The main performances are Chiwetel Ejiofor, Lupita Nyong'o, Fassbender. These are such demanding parts. These guys had to keep themselves in a perpetual state of angst and foreboding and longing and they did it, they did it. They held themselves through the entire filming process."
And Pitt is convinced 12 Years A Slave will have film fans talking for years to come: "I know what this film is. I've been around film long enough. I know the impact, and this one will have a continuing impact... It's one of those few films that cuts to the base of our humanity. And it was not until I saw Solomon Northup's story that I fully, fully grasped the utter horror of losing your freedom or denying another one their freedom, taking their freedom, splitting their family apart."
Fassbender, who stars as a sadistic plantation owner, has emerged as an early frontrunner for the Best Supporting Actor category at next year's (14) Oscars, but he recently told GQ magazine he would not be spending months campaigning for awards recognition.
He said, "I'm not a politician. I'm an actor. It's just a grind."