Casting
Fuqua met studio executives to see possible actors for the film, and saw that they were all white. He found this to be problematic, as he wanted to make the cast diverse. Fuqua worked to create this diverse cast by incorporating actors of color, such as African-American Denzel Washington, Korean Lee Byung-hun and Mexican Manuel Garcia-Rulfo, and making sure the female lead Emma Cullen (Haley Bennett) did not conform to stereotypes. It is a decision, Fuqua stated, that reflects historical reality more than it does any conscious attempt to update the story: "There were a lot of black cowboys, a lot of Native Americans; Asians working on the railroads. The truth of the West is more modern than the movies have been".
The actors were cast between December 2014 and July 2015. At one point, Jason Momoa was in talks to join the project, but had to leave because he was already cast to play Aquaman. The cast were put through cowboy training before filming commenced, and were sent to boot camp to hone their skills.
Denzel Washington's character, warrant officer and bounty-hunter Sam Chisolm, was renamed from Chris Adams, played by Yul Brynner in the original film. It is Washington's first Western film. Washington did not watch Western films growing up, as it was the end of the Western era in cinema. He and his siblings were not permitted to go to the movies by his father, a Church of God in Christ minister. They grew up watching biblical films instead, like King of Kings and The Ten Commandments, though he did watch portions of the Rawhide and Bonanza shows. Washington did not watch the 1960 film in preparation, but had seen Seven Samurai. This was an arbitrary decision of his, since he thought that watching the 1960 film would not help him: "[Not seeing it] allowed me to do whatever I wanted to do. Instead of trying not to do what someone else did."
As with his previous films, Washington would start off the day by kneeling down and praying, asking for forgiveness for all his wrongdoings. "For me," he said, "this is more than just making movies. It is a platform." Fuqua said that Washington, with whom he had twice collaborated, was his first choice to be cast irrespective of the role. The producers were skeptical whether Washington would take the job since it was a Western film, but Fuqua flew to New York City to negotiate with the actor, who accepted the offer.
Chris Pratt described his character Josh Faraday as "a bit of a fox, a trickster. He's a gambler, a drinker. He loves the ladies. But he's deadly in a fire fight." Like Washington, it is also Pratt's first Western film. Pratt began watching Western films at the age of 31, while filming in London, and credits Gary Cooper for revitalizing his perspective towards the genre. Fuqua, aware of Pratt's penchant towards Westerns, reached out to him, and Pratt called back in a few days singing "Oh Shenandoah", to which Fuqua replied, "He's it. He's Steve McQueen."
Fuqua's approach to Ethan Hawke's character Goodnight Robicheaux, a former Confederate soldier, was to picture him as if Christopher Walken's character Nikanor "Nick" Chevotarevich in The Deer Hunter was an emotionally shattered Civil War veteran. Hawke was the first person to come on board after the project was finalized. He had stumbled upon Fuqua and Washington during the New York City premiere of The Equalizer in 2014 and, upon learning that a remake was in the works, asked Fuqua to cast him. Like Washington, The Magnificent Seven marks the third collaboration between Hawke and Fuqua, after Training Day (2001) and Brooklyn's Finest (2009).
Manuel Garcia-Rulfo described his character Vasquez, a bandit on the run from the law, as someone who loves gunfighting.
Martin Sensmeier auditioned several times to land the role of Red Harvest, a native Comanche warrior. He stayed off social media and studied intently to portray his part. Scotty Augere, who had previously worked on Dances with Wolves, taught Sensmeier how to ride a horse bareback and rode with him two hours a day.
Vincent D'Onofrio was cast as mountain man Jack Horne on the urging of co-stars Chris Pratt and Ethan Hawke. For the role, D'Onofrio developed a raw, high-pitched voice to give the impression of a man who has lived in the wilderness for years without speaking to people. When he asked to test the voice for Fuqua, the director refused to listen, instructing the actor to surprise him with it in his first scene, which resulted in a delighted Fuqua laughing so hard that he almost ruined the take.
