Ryan Reynolds, 42, took to his Twitter to “thank” the late star for “everything”.
In view of his 12 million followers, the actor shared a picture of Stan appearing to be making a speech.
He captioned the picture: “Damn… RIP Stan. Thanks for everything.”
Actress Tara Strong, 45, said she is “heartbroken” to hear about the loss of Stan Lee in a lengthy statement.
How did Stan Lee die? What was his cause of death?
Taking to her Twitter with 369,000 followers, she tweeted: “I’m heartbroken. I don’t have the words. Legend.
“There was never anyone like him & there never will be again.
“@TheRealStanLee was a trailblazer. A genius. And modest. On #SPIDERMAN-Animated he came on to do some voices.
“I asked him how it felt to have created such iconic characters & he replied, ‘I always had a great team’.
She added: “He was in great shape mentally and physically. I asked him his secret.
“He said, ‘Never retire. Do what you love & never stop’. At cons he was hilarious & kind.
“He liked me to sit with him & he was always gracious to his fans.”
Alongside a picture of her with Stan Lee, she added: “Love you @TheRealStanLee, hope you’re still creating heroes & dreams in the sky.”
The Spider-Man co-creator reportedly died early hours this morning at California’s Cedars-Sinai Medical Center, TMZ reports.
Stan Lee’s daughter Joan Celia Lee told the news website: “My father loved all of his fans. He was the greatest, most decent man.”
Elsewhere, other fans of Stan Lee from the showbiz world have paid their respect online.
The Avengers star Chris Evans posted a heartfelt tribute.
He wrote: “There will never be another Stan Lee.
“For decades he provided both young and old with adventure, escape, comfort, confidence, inspiration, strength, friendship and joy.
“He exuded love and kindness and will leave an indelible mark on so, so, so many lives. Excelsior!!”
Rapper Travis Scott penned: “Thank u Stan Lee for everything.”
Superbad actor Seth Rogen added: “Thank you Stan Lee for making people who feel different realize they are special.”