Production notes

On 17 June 2020, it was announced that Pablo Larraín would direct Spencer, a film starring Kristen Stewart as Diana, Princess of Wales. On 26 June 2020, it was reported that Neon and Topic Studios had acquired the rights to distribute the film in the United States for $4 million in a bidding war that reportedly also included Searchlight Pictures, Universal Pictures and A24. In July 2020, STX Entertainment acquired rights to the film in the United Kingdom, France, Italy and the Benelux, while DCM Film Distribution was set to distribute the film in Germany and Switzerland.

Filming began at the Schlosshotel Kronberg, Germany, in January 2021 with Timothy Spall, Sally Hawkins, and Sean Harris joining the cast. Other filming locations were the Schloss Marquardt in Marquardt, north of the city of Potsdam, and Nordkirchen Castle, the moated castle. During the fall of 2020, Larraín and Production Designer Guy Hendrix Dyas embarked on an intense scout in search of the perfect location. Sandringham House is a British institution set within the picturesque landscape of Norfolk. The fore mentioned Nordkirchen Castle was exactly what the script called for, grand and impressive, yet isolated. "An Elegant prison" was the exact expression coined by Larraín and Dyas to convey the overall sentiment to the rest of the crew. Somewhere where you wouldn't necessarily enjoy spending Christmas, where you get the subtle feeling that underneath the festivities there's a real anguish and misery at play. On 25 March, production moved to the UK for the final stretch of filming, with Jack Farthing joining the cast as Prince Charles, and the film wrapped on 27 April 2021. The film was shot on both Kodak Super 16mm and 35mm film stock by cinematographer Claire Mathon using the Arricam LT, and Arriflex 416 Plus. To achieve the film's specific look, she used a combination of Leitz Summilux and Zeiss Ultra 16 lenses. In an interview with Kodak, Mathon said that shooting on film was their obvious choice, calling it a "necessity" and that "there was never a question about shooting digital or film". According to her, the only question was whether they would shoot the film in 16mm or 35mm film stock. She also revealed that she and Larraín reviewed sequences from various Stanley Kubrick films such as Barry Lyndon (1975) and A Clockwork Orange (1971) to learn about the style of camera movement, rhythm of the shots, and the use of short focal lenses. Most of the film was shot on Super 16mm film format due to the lightness, and ergonomics of the equipment used while also revealing that economic advantages is also part of the reason. In some scenes where they wanted to minimize the grain, they opted for the 35mm film stock as it retains both softness and details on the darker part of the image. Film processing and 4K 16-bit scans were done at Hiventy in Paris, while the cameras were supported by Arri Rental in Berlin, Germany.

Jonny Greenwood composed the score. The score was released by Mercury KX on 12 November 2021. Writing for the You Discover Music website, Sharon Kelly described the soundtrack, stating: "Jonny Greenwood's genre bending music for the Spencer soundtrack combines free jazz and classical baroque."

Spencer grossed more than $7 million in the United States and Canada, and $18.1 million in other territories, for a worldwide total of $25.2 million. In the United States and Canada, Spencer made $2.1 million from 996 theatres in its opening weekend. In its second weekend, the film played in 1,265 theatres and made $1.53 million.

Upon the teaser trailer's release, Forbes reported that the role "thrusts" Stewart "into the Oscar race" for the Academy Award for Best Actress. After the film's world premiere, Variety also stated, "There's already been plenty of talk in Venice that the role will likely land Stewart her first Oscar nomination." The film received a three-minute standing ovation at its world premiere, with critics lauding Stewart's performance as Diana. On review aggregator Rotten Tomatoes, 83% of 351 critics have given the film a positive review, with an average rating of 7.6/10. The website's critics consensus reads: "Spencer can frustrate with its idiosyncratic depiction of its subject's life, but Kristen Stewart's finely modulated performance anchors the film's flights of fancy." On Metacritic, the film has a weighted average score of 76 out of 100, based on 53 critics, indicating "generally favorable reviews". David Rooney of The Hollywood Reporter stated that the film "rests on Stewart's shoulders and she commits to the film's slightly bonkers excesses as much as to its moments of delicate illumination" and wrote that "[not] everything lands in Spencer, and I often wondered if the film was so set on bucking convention that it would alienate its audience. But it tells a sorrowful story we all think we know in a new and genuinely disturbing light." Reviewing the film for The Daily Telegraph, Robbie Collin wrote: "The 31-year-old Stewart – who will be instantly and justifiably awards-tipped for this – navigates this perilous terrain with total mastery, getting the voice and mannerisms just right but vamping everything up just a notch, in order to better lean into the film's melodramatic, paranoiac and absurdist swerves." Drawing comparisons between the film and the Jacqueline Kennedy biopic Jackie (2016), also directed by Larraín, Pete Hammond of Deadline Hollywood stated that "Spencer is something else indeed, almost playing out in a conventional dramatic fashion, a more accessible approach in some ways, but also more ambitious as it is squarely from the point of view of its title character, purposely called Spencer to assure us that the person who once was, is well on the way to finding that very lost spirit again before it is too late." Spencer was listed on many critics' top ten lists for 2021.

Stewart's portrayal of Diana was hailed as one of the most accurate portrayals of the late Princess. Ken Wharfe, Diana's former bodyguard, commented, "Out of all the people who have played Diana over the past 10 years, she's the closest to her. She managed to perfect her mannerisms." Former Royal Chef Darren McGrady, who was portrayed by actor Sean Harris in the film, said, "Kristen Stewart is amazing as the princess, with her mannerisms and her voice ... the happy scenes of her with the boys, it was like her coming alive again. For real, Kristen Stewart played an amazing part." However, McGrady also pointed out that the film took considerable liberties, especially with its use of metaphors, but acknowledged that the film was a fictionalised take on what possibly could have happened.