Actor Brian Cox will lend his voice to Santa Claus for Netflix's upcoming animation feature titled That Christmas. Set for a 2024 release, That Christmas is an adaptation of the eponymous children's book series by writer-director-author Richard Curtis. It is the first feature film of Simon Otto as a director. Otto is considered a veteran in animation and is best known for the animation short story collection Love, Death + Robots and for his behind-the-scenes work on the How to Train Your Dragon films.

Cox joins a lineup of voice cast members for That Christmas, which comprises Bill Nighy, Fiona Shaw, Jodie Whittaker, Lolly Adefope, Katherine Parkinson, Alex Macqueen, India Brown, Sindhu Vee, Sienna Sayer, Zazie Hayhurst, Rosie Cavaliero, Jack Wisniewski, Guz Khan, Paul Kaye, Kuhu Agarwal, Andy Nyman, Freddie Spry, Rhys Darby, and Ava Talbot.

That Christmas is a Locksmith Animation production and will have animation production work from DNEG. Adam Tandy and Nicole P. Hearon are the producers of the film. On the other hand, the executive production team comprises Natalie Fischer, Mary Coleman, Elisabeth Murdoch, Julie Lockhart, Lara Breay, Bonnie Arnold, Rebecca Cobb, Sarah Smith, Curtis, and Colin Hopkins.

Cox was last seen in Dean Israelite's Little Wing.