Patricia Rooney Mara ( MAIR-ə; born April 17, 1985) is an American actress and fashion designer. She began her career playing supporting roles in several independent films, including the coming-of-age drama film Tanner Hall (2009), before starring as Nancy Thompson in the 2010 remake of A Nightmare on Elm Street and as Erica Albright in the biographical drama film The Social Network (2010).

In 2011, Mara had a career breakthrough when she portrayed Lisbeth Salander, the title character in David Fincher's The Girl with the Dragon Tattoo, based on Stieg Larsson's Millennium book series. She received critical acclaim for her performance and was nominated for an Academy Award for Best Actress and a Golden Globe Award for Best Actress in a Motion Picture – Drama. In 2013, she starred in the thriller Side Effects, the independent drama Ain't Them Bodies Saints and the acclaimed sci-fi romantic drama, Her. The following year, she starred in the adventure drama film Trash (2014). In 2015, she garnered further critical acclaim for her performance in Todd Haynes' romantic drama Carol, for which she tied for the Best Actress Award at the 2015 Cannes Film Festival, and received nominations for the Golden Globe Award for Best Actress in a Motion Picture – Drama, SAG Award, BAFTA Award and Academy Award for Best Supporting Actress.

Mara is also known for her charity work and oversees the charity Uweza Foundation, which supports empowerment programs for children and families in the Kibera slum of Nairobi, Kenya, one of the largest slums in Africa.