The cast of Quentin Tarantino's Once Upon a Time in Hollywood keeps growing, with Scoot McNairy, coming aboard for a supporting role. The actor will portray a character known as Business Bob Gilbert, a cowboy who plays a role on a popular Western TV series. Leonardo DiCaprio's main character Rick Dalton is said to be the lead character of a former hit Western series, so it's possible that Gilbert is one of Dalton's co-stars, but that has yet to be confirmed.

The story centers around DiCaprio's Rick Dalton and Brad Pitt's Cliff Booth, Dalton's longtime stunt double on the Western TV series. Both men find themselves struggling to find a place in a new Hollywood that embraces the counter-culture values of the 1960s, that they don't recognize one bit. Their plot thickens when Dalton gets a new next door neighbor, an up and coming young actress named Sharon Tate, who will be reportedly played by Margot Robbie. The story will take place in the summer of 1969, which will include her death on August 9, 1969, by members of the Manson Family, which shook Hollywood to its core.

The ensemble cast also includes Al Pacino as a fictional talent agent named Marvin Schwanz, Dakota Fanning as Squeaky Fromme, one of the Manson Family members, Emile Hirsch as Jay Sebring, the Hollywood hair stylist who was one of the four people murdered at Tate's house, Damian Lewis as Hollywood icon Steve McQueen, a close friend of Tate and Sebring who was supposed to be there the night of the murders and Burt Reynolds as George Spahn, who owned the ranch that the Manson Family stayed at while they planned the murders. The Manson Family did not intend to kill Tate that night, but rather a record executive who used to live there, and who turned down Manson's record demo.

Related: Quentin Tarantino's Once Upon a Time in Hollywood Trailer Has Arrived

The cast also includes Clifton Collins Jr. as Ernesto the Mexican Vaquero, Luke Perry as Scott Lancer, Nicholas Hammond as British director Sam Wanamaker, Keith Jefferson as Land Pirate Keith, plus Michael Madsen, Kurt Russell, Tim Roth and Timothy Olyphant in unspecified roles. Tarantino is directing from his own screenplay, while also producing alongside David Heyman and Shannon McIntosh. Sony Pictures has set an August 9, 2019 release date, which marks exactly the 50th Anniversary of the infamous Sharon Tate murders. As of now, the movie will go up against Disney's Artemis Fowl.

Production is supposed to get under way this summer, but no exact filming start date has been released, and there is no indication yet as to how many more roles still need to be cast for this sprawling ensemble, that will be shot throughout Los Angeles this summer. This will be Quentin Tarantino's ninth film in total, and the director has said in numerous interviews that he plans on retiring from filmmaking after his 10th film. McNairy stars in the hit shows Godless for Netflix and Halt and Catch Fire for AMC, and he's currently filming a lead role for the new season of True Detective on HBO. He'll next be seen on the big screen in The Legacy of a Whitetail Deer Hunter, alongside Josh Brolin, Danny McBride and Carrie Coon.|Deadline broke the news on Scoot McNairy's casting in Once Upon a Time in Hollywood.