On Friday, the filmmaker informed Pixar employees of his decision. "I'm not leaving to make films at another studio; instead, I look forward to spending much-needed time with my family and pursuing interests that have long been back-burnered," said Unkrich, 51, in a statement to The Hollywood Reporter.

On Saturday, Unkrich tweeted a letter he sent to his colleagues at Pixar. "It is impossible for me to adequately express how epic this twenty-five-year journey has been, and how much it has meant to work alongside such fantastic people and phenomenal talents," he wrote. "Many of you are like family to me, and it's nearly incomprehensible to imagine no longer being here at Pixar with you."

Sources say the departure is amicable, with Unkrich leaving on a high note: Coco made over $807 million worldwide and won the best animated feature Academy Award at the 2018 Oscar ceremonies. He is said not to have started on any new projects.

Unkrich's departure comes during a time of change at Pixar and in the animation industry in general. His mentor, Pixar co-founder John Lasseter, left his post at the company and Walt Disney Animation under a cloud of workplace misconduct, and has now resurfaced at Skydance Animation.

Unkrich's Pixar colleagues were effusive with praise.

"Lee arrived at Pixar as we were crafting Toy Story, and he's had a profound effect on all Pixar films since. He literally taught us rookie filmmakers about staging, composition and cutting," said Pete Docter, who directed Monsters, Inc. and became Pixar's chief creative officer after Lasseter's exit. "His artistry and expert craftsmanship as an editor and co-director became a major reason for the high quality of our filmmaking, and as Lee went on to direct, his ability to find the deep humor and emotion enabled him to create some of the strongest films we've made."

"If you look at the sweep of contemporary cinema, it would be difficult to find someone more brilliant in the filmmaking arts than Lee Unkrich," said Pixar president Jim Morris. "He has been a key player in elevating virtually every one of Pixar's films."

Said Walt Disney Studios chairman Alan Horn: "Lee has left an indelible mark on the world of film, and we are so grateful for the passion and talent he has brought to each movie he has worked on. He'll always be part of the Disney-Pixar family, and we will miss him."