Rob Gibbs, a story artist, director and animator, died aged 55.

Most of us grew up watching Monsters, Inc., Toy Story, Finding Nemo, and more animated films. And it's unfortunate one of the animators behind our beloved films has died.

Rob had been working for Disney for around 22 years.

At the time of his death, Rob, a resident of San Rafael, California, was co-directing and in preproduction on Hump. He was also working on the upcoming Monsters, Inc. spin-off series Monsters At Work.

When Rob Gibbs first joined Disney, he worked in Story and Visual Development in Disney Feature Animation for five years.

During his time there, he worked on films including Pocahantas and Fantasia 2000.

Rob later moved to Pixar, where he contributed to several classic children's films such as Toy Story 2, Wall-E, Brave, Inside Out, Incredibles 2, and Onward.

His daughter, Mary, even voiced the well-loved character of Boo in Monsters, Inc.

Following news of his death, MovieBrats Pictures co-founder, Alexander Weimer, paid tribute to the animator on Facebook, writing:

"Our hearts broke this morning when we learned of the sudden passing of Rob Gibbs, co-director of our animated film HUMP."

"We've not only lost a creative partner, but also a wonderful human being, always in a good mood and never short of a joke that made it a joy to work with him over the past few years."

"Before we met Rob, he already looked back at an impressive career at Disney and Pixar… and he kept entertaining us with his anecdotal stories from his many years in the industry."

"He loved spending time with his daughter, and he loved old classic cars and zombie stories. You'll be dearly missed, Rob."

Daniel Chong, a fellow animator, and creator of Cartoon Network's We Bare Bears, also shared his tribute on Twitter.

He tweeted:

"Heartbroken over the loss of Rob Gibbs. If you or your kids have seen any Pixar CarsToons shorts, Rob directed most of 'em."

"His daughter was the voice of Boo in Monsters, Inc. He was such a positive, hilarious, and heartfelt guy, who cared a lot for his crew. Will miss him."

Many fans have also taken to social media to mourn the loss of an incredible man who made our childhoods the best they could be.

One person wrote:

"I don't know much about Rob Gibbs but the fact that he was part of creating some of the movies that I love and treasure up to this day really makes me sad. Thank you for your work and artistry."

Another said:

"I found out that storyboard artist and director Rob Gibbs has died today. Noted for his amazing work at Pixar, he worked at the studio for over twenty years…I'm really gonna miss him."