Meet Sox, the surprise superstar of Pixar's Lightyear

Of all the stars in the galaxy, none burn quite as bright as Sox, the personal companion robot introduced in Pixar's Lightyear.

The animated adventure, which is the fictional sci-fi movie that inspired the Buzz Lightyear action figure in Toy Story, sees the Chris Evans-voiced Space Ranger marooned with his crew on a hostile planet. In an attempt to get everyone home safely, Buzz test pilots a ship fueled by a hyper-speed crystal and inadvertently travels years into the future. Upon reentry, Starfleet assigns him Sox to help ease his transition into the current time.

Part BB-8 from Star Wars, part Goose from Captain Marvel, Sox, the robo-cat voiced by actor Peter Sohn, single-handedly emits so much joy in Lightyear, whether his robot paws are frantically typing away on a computer keyboard in a piece of animated physical comedy or he's shooting sleep darts out of the trick compartment in his mouth. (Watch the clip above to see the 'bot try to soothe an irritated Buzz by playing calming sleep sounds.)

Disney/Pixar Sox (voiced by Peter Sohn) and Buzz (Chris Evans) in 'Lightyear'.

Director Angus MacLane knew right away that Sox would be a hit. Sohn, who works at Pixar across the animation department and voice acting realm, had previously voiced characters like Forrest Woodbush/the Pet Collector in The Good Dinosaur, Squishy in Monsters University, Emile in Ratatouille, and more recently Ciccio in Luca. Sohn was already in the studio early on in the process giving voice to the character before he had been officially cast. MacLane could already tell what was working about his deliveries at that time.

"Sox was one of the first character models that were built. So once we saw the animation of the funny puppet mouth and all of that, it was really easy to imagine what that would look like," MacLane tells EW a day after Lightyear had its Hollywood premiere last week. "The comedy contrast between the realistic world of Buzz and hard suits and all this, and this funny cat, you could see it in the screening last night."

The world premiere was the first time MacLane and his producer Galyn Susman had seen Lightyear with a live audience. Usually Pixar films undergo a series of "Brain Trust" screenings, in which the creators show cuts of their work to various employees at Pixar, especially those who aren't involved on the project whatsoever. Susman says they usually do about eight rounds of screenings on any given film, but because of COVID-19, that wasn't possible.

Disney/Pixar Disney's 'Lightyear.'

Where normally she and MacLane would sit in a theater of 250-plus people and see the live reactions to what was working and what wasn't, she says, "We would send out a link and wait to get their notes."

One of those notes, she remembers, was "more Sox!" Others, according to MacLane, were "too much robot talking cat" and "you gotta get a new voice for Sox." So it wasn't always super helpful. But the premiere screening with the cast in attendance confirmed their long-held belief.

"Not to spoil anything, but people were really excited about seeing him at the end," MacLane says. "He's in there just enough not to over weigh the movie towards the Sox picture."

Lightyear is currently playing in theaters.

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