Fares was born in Beirut, Lebanon. His younger brother is Director Josef Fares, and he has four sisters. In 1987, when Fares was 14 years old, his family moved to Sweden, residing in Örebro. They moved to escape the Lebanese Civil War and chose Sweden because they had relatives who had already lived there. Fares says he learned Swedish within three months of living in Sweden.
Fares has played major parts in his brother, Director Josef Fares' films, including his debut acting performance in 2000's Jalla! Jalla! and 2003's Kopps. He starred in Bang Bang Orangutang (2005) and Kill Your Darlings (2006).
In 2010, Fares starred in the Swedish crime thriller Easy Money with Joel Kinnaman. The film was critically acclaimed and was picked up for American distribution by Harvey Weinstein. In 2012, Fares made his Hollywood debut in the Denzel Washington movie Safe House. He played CIA officer Hakim in Zero Dark Thirty. Fares had a role in Child 44 (2014) with Tom Hardy and Gary Oldman. Fares played Senator Vaspar in the popular Star Wars franchise movie Rogue One: A Star Wars Story (2016).
For 2013's Kvinden i buret (English title: The Keeper of Lost Causes), which was set in Denmark, Fares learned to speak Danish. Keeper of Lost Causes is based on a novel by Jussi Adler-Olsen, the first of four features based on his Department Q novels. Fares and Nikolaj Lie Kaas will appear in all four films. Keeper of Lost Causes was Denmark's top film of 2013. Fasandræberne (English title: The Absent One) is the second film in the series. It also broke Danish film grosses, setting new records. The third film in the series, A Conspiracy of Faith (Flaskepost fra P), premiered in Denmark in March 2016 and in the United States in June.
In 2014, Fares portrayed Fauzi Nadal in the TV show, Tyrant, on the FX Network. Tyrant was renewed for a second season, which began airing in the summer of 2015, and a third season in summer 2016.
