Sox is played by Peter Sohn, who has worked for Pixar Animation Studios since 2003 but started voice work later. A trained animator and storyboard artist, Sohn has applied his technical craft to Finding Nemo, The Incredibles, Ratatouille, Wall-E, Up, and Toy Story 3. Sohn eventually became a director and producer at Pixar, where he directed his first feature film The Good Dinosaur in 2015 and executive produced Luca in 2021.
Sohn first began voicing characters for Pixar in 2004, when he provided additional voices for The Incredibles, according to his IMDb. He has since voiced Emile in Ratatouille and Squishy in Monsters University. However, Sox is his most prominent voice acting role to date.
The Pixar veteran was an easy choice when it came to casting Sox, says Lightyear director Angus MacLane. “He was our scratch voice or temporary voice for the character,” MacLane said on Beyond The Trailer. But Sohn won over the producers with his performance as well as his warm personality as a collaborator. “He’s so funny and so adorable. The way everyone thinks about Sox is what we think about Peter.”
MacLane went on to share that Sohn was the inspiration behind Russell in Up, although there would have been some issues playing the youngster. MacLane says son would have voiced Russell “if he hadn’t sounded like a 35-year-old guy.” Luckily, Sohn’s voice works fine for a robotic cat.