Carol Burnett honors Bob Newhart: 'As kind and nice as he was funny'

Bob Newhart didn’t just fill bellies with laughter. He also touched hearts.

The comedy icon, best known for starring in the sitcoms "The Bob Newhart Show" and "Newhart," died Thursday following a series of short illnesses. He was 94.

Actress and fellow comedy legend Carol Burnett paid tribute to Newhart in an emotional post on X. Newhart guest-starred on Burnett's sketch-comedy series "The Carol Burnett Show" in 1971.

"I had the great pleasure of working with Bob and being his friend," Burnett wrote alongside a black-and-white photo of the pair. "He was as kind and nice as he was funny. He will be missed."

Several stars have taken to social media to share their appreciation for Newhart and his entertainment legacy.

Bob Newhart dies: Sitcom star and deadpan comedy legend was 94

'Big Bang Theory' co-star Kaley Cuoco: 'Icon forever'

Kaley Cuoco, who played Penny on "Big Bang Theory," expressed her gratitude for the opportunity to work with Newhart, who portrayed Professor Proton aka Arthur Jeffries.

“What a dream it was to witness the genius that was Bob Newhart. He was classy, kind, generous and absolutely hilarious. Every take — every time. Icon forever," she wrote in an Instagram Story Thursday.

Co-creator of the CBS sitcom Bill Prady also fondly remembered working with the comedy legend.

"Hard to explain how important Bob Newhart was to every comedian and comedy writer who came after him," Prady wrote on X. "Working with him ever so briefly was one of the greatest joys and honors of my life."

Jamie Lee Curtis, Mark Hamill, more praise 'funny' Bob Newhart

Jamie Lee Curtis shared a throwback photo of Newhart posing next to an Emmy Award statuette. Newhart won a Primetime Emmy for outstanding guest actor in a comedy series in 2013 for his performance on "The Big Bang Theory."

"They will be laughing wherever people go when they leave us. God, he was funny!" Curtis wrote on Instagram. "Bob Newhart. You will be missed!"

"From his groundbreaking stand-up to his two classic sitcoms he gave us a lifetime of laughter," Mark Hamill wrote on X. "Truly one-of-a-kind. Thank you Bob Newhart!"

Comedian Dane Cook wrote on X that Newhart is "forever funny."

"His album The Button-Down Mind of Bob Newhart impacted my career intensely," Cook wrote. "He was and is one of the best comedians to ever deliver and man he delivered. Always funny. Always from the heart. Always a reminder to me of why I started in stand up."

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Ben Stiller, Judd Apatow remember Bob Newhart's kindness and comedy chops

"Bob Newhart. What a career," Ben Stiller wrote on X. "An iconic comedic actor. I and so many people grew up watching him. He was so subtle and had a brilliant sense of timing and understatement. And an incredibly kind man. Sending love to his family."

Judd Apatow gushed that Newhart "made the world a better place for a really long time."

"Bob Newhart was the kindest most hilarious man," Apatow wrote on X. "He asked me to make a documentary about his friendship with Don Rickles. I was so lucky to get to spend that time with my hero.

"His brilliant comedy and gentle spirit made everyone he encountered so happy."

TBS pays tribute to Professor Proton with 'Big Bang Theory' marathon

"Big Bang Theory" fans will be able to celebrate Newhart's legacy with a "best of Professor Proton" marathon on Sunday, July 21. Here are the episodes that will air beginning at 8 p.m.

• Season 6, Episode 22: "The Proton Resurgence"

• Season 7, Episode 7: "The Proton Displacement"

• Season 7, Episode 22: "The Proton Transmogrification"

• Season 9, Episode 11: "The Opening Night Excitation"

• Season 11, Episode 6: "The Proton Regeneration"

• Season 12, Episode 5: "The Planetarium Collision"

Contributing: Bill Keveney and KiMi Robinson

This article originally appeared on USA TODAY: Bob Newhart tributes: Carol Burnett, Kaley Cuoco, more stars