Director
Bertrand Bonello started writing the screenplay in 2017 with
Gaspard Ulliel and
Léa Seydoux in mind for the lead roles, after having worked with both actors in
Saint Laurent (2014). The project was officially announced in January 2021, but filming was postponed due to the COVID-19 pandemic and was scheduled to start in April 2022. In the meantime, Bonello directed the film
Coma (2022) instead, which featured Ulliel in the last movie he filmed and the last work he finished. Ulliel passed away on January 19, 2022 following a skiing accident, and the filming for 'The Beast' was delayed again. In February 2022, Bonello told Variety that he would likely recast Ulliel's role with a non-French actor. On May 16, 2022, it was announced that British actor
George MacKay was cast as the male lead and that filming was scheduled to start in August 2022.
