James Marsden and “American Housewife” actress Julia Butters will join the cast of Quentin Tarantino’s film “Once Upon a Time in Hollywood,” sources tell Variety.

Insiders would not reveal what roles Marsden and Butters will be playing.

Damian Lewis, meanwhile, will portray acting icon Steve McQueen, Luke Perry is Scotty Lancer, Emile Hirsch is hairstylist Jay Sebring, Dakota Fanning is Lynette “Squeaky” Fromme — a member of the Manson family — Clifton Collins is Ernesto the Mexican Vaquero, Keith Jefferson is Land Pirate Keith, and Nicholas Hammond is director Sam Wanamaker.

The movie, which Tarantino is writing, directing, and producing, also stars Leonardo DiCaprio, Brad Pitt, Margot Robbie, Burt Reynolds, and Timothy Olyphant. Al Pacino just joined the cast as DiCaprio’s character’s agent.

David Heyman and Shannon McIntosh are producing as well.

The pic takes place in Los Angeles in 1969. The two lead characters are Rick Dalton (DiCaprio), the former star of a western TV series, and his longtime stunt double, Cliff Booth (Pitt). Both are struggling to make it in a Hollywood they no longer recognize. But Dalton has a very famous next-door neighbor … Sharon Tate.

The film will be released worldwide on Aug. 9, 2019 — the 50th anniversary of the day that the Manson family committed the LaBianca murders and the day after Tate was killed.

Marsden can currently be seen as Teddy on HBO’s “Westworld,” which is in its second season and continues to be one of the cabler’s most popular shows. He is also active on the film front, having most recently appeared in Rob Reiner’s “Shock and Awe.”

Marsden has signed on to star in Paramount’s “Sonic the Hedgehog” movie. He is represented by CAA, Authentic Talent, and Literary Management.

Butters is best known for her work on “American Housewife,” and has also appeared in the films “13 Hours” and “A Family Man.” She is repped by CESD.