Phil Donahue was remembered as a legend in the entertainment industry as tributes poured in across social media for the iconic talk show host.

The Emmy Award-winning journalist died Sunday following a long illness, his family told NBC's "Today." He was 88.

Marlo Thomas, his beloved wife of over 40 years, paid tribute to her late husband on Instagram on Monday, sharing "one of [her] favorite photos" of her and Donahue, featuring the two of them riding on a moped while on vacation together many years ago.

"I'm sure by now you've heard the very sad news that I lost my sweetheart last night, so I know you understand that I'll be stepping away from this page for a while to take care of myself and the many people who took care of Phil, and held him close to their hearts," she wrote in the caption.

Phil Donahue and Marlo Thomas at the premiere of Hilary.

Thomas thanked her fans for their support following the loss of her husband. (Andrew H Walker/Variety/Penske Media via Getty Images)

TALK SHOW ICON PHIL DONAHUE DEAD AT 88

She continued: "But I didn't want to disappear without saying thank you for the beautiful messages of love and support that have been coming in all day, and for the wonderful and generous way that you've let Phil and me share our life adventure with you over the years. As a man who spent his career loving his audiences, Phil got such a kick out of our cozy little community here, and I know he would be very touched by the heartwarming thoughts and memories you've been sharing."

"Until I return, I wish you good health and happy days in the company of family and friends, and I hope that you will continue to hold close those you cherish most, just as I was blessed to do with my beloved Phillip," she concluded, signing off with "love, Marlo."

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Montel Williams also shared a statement with People, calling Donahue "the true godfather of the talk show genre."

"With a heavy heart, I bid farewell to Phil Donahue, the true godfather of the talk show genre. Phil pioneered audience participation on critical issues, setting the standard for all of us who followed," he wrote. "His contributions to television and dialogue on important societal topics are immeasurable," he continued. "My deepest condolences go out to his family during this time. Rest in peace, Phil—you will be missed but never forgotten."

Phil Donahue portrait

Phil Donahue died on Sunday night following a long illness, his family told NBC’s "Today." (Michel Delsol/Getty Images)

Actress Sarah Jessica Parker shared her feelings on Instagram, writing "Phil Donahue, we loved you."

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"Thank you for multiple decades of smart, funny, informative and often very brave television," she wrote. "We honor you, your work and your devotion to your audience. To @marlothomas and his family, my sincere condolences. RIP and Godspeed. X, SJ."

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Academy Award-nominated actress and talk show host, Oprah Winfrey called Donahue a "pioneer," and credited him for championing her during the early days of her career.

"There wouldn’t have been an Oprah Show without Phil Donahue being the first to prove that daytime talk and women watching should be taken seriously," she wrote alongside a black and white photo of them together. "He was a pioneer. I’m glad I got to thank him for it. Rest in peace Phil."

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In a statement to People, Ricki Lake shared she "greatly admired" Donahue and that she was "honored" to have known him, adding that he "will be greatly missed and what a legacy he has left behind!"

Phil Donahue talk show

Phil Donahue hosted "The Phil Donahue Show" from 1967 to 1996. (Bettmann/Contributor)

Director Michael Moore shared his tribute to his "good friend" Donahue on X, formerly known as Twitter," sharing photos of the two of them out to dinner together.

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"My good friend Phil Donahue has passed away. Fearless. Brave. Would not back down. Gave voice to the voiceless. He was removed from TV for his outspoken stand against the Iraq War. Made one of the best docs ever- BODY OF WAR(2007). He was kind, giving, relentless. An inspiration."

Amy Sedaris shared a photo of Donahue on the cover of People Magazine in 1976, writing, "Very sad news. My family grew up watching his show. We saw and learned so much."

Musician Questlove shared how Donahue impacted his worldview as a kid, noting his death marks the "end of an era."

"End of an era. Sick days from school for Gen X meant starting with Phil Donahue," he wrote, adding: "Who before Oprah owned the lane was the standard of the modern morning talk show in which red state & blue state America realized HOW different (& alike?) we were? rest in peace."

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Fox News Digital's Tracy Wright contributed to this report