This article contains some spoilers for Star Wars: The Rise of Skywalker.
When Carrie Fisher passed away in 2016, Star Wars fans were heartbroken. They were also concerned about the role General Leia Organa would play in the then-yet to be filmed third installment in the final trilogy of the Skywalker saga. Director J.J. Abrams and Lucasfilm president Kathleen Kennedy made the decision not to digitally recreate Fisher for Star Wars: The Rise of Skywalker, but to instead use footage she had already shot for the earlier films and work them into the plot.
Of course, a lot of digital work had to be done to blend Leia into scenes with the actors. IGN got a chance to speak to some of the visual effects department for the film, including visual effects supervisor Roger Guyett, creature effects supervisor Neal Scanlan and ILM visual effects supervisor Patrick Tuback about what it took to bring Princess Leia back for the final chapter in the Skywalker Saga.
Source: IGN.com How the Rise of Skywalker VFX Team Pulled Off Carrie Fisher's Scenes