Elon Musk, Ryan Reynolds and British film director Edgar Wright were among those who admired and worked with him to share their memories.
Avengers and Captain America actor Chris Evans said he was one of a kind, adding the writer's catchphrase, "Excelsior!" while Wolverine actor Hugh Jackman said he was "a pioneering force in the superhero universe. I’m proud to have been a small part of his legacy."
Lee was behind countless comic characters which have "inspired generations", said his fans.
He died today aged 95. His death was announced by his daughter JC.
Iron Man actor Robert Downey Jr said he "owed it all" to Lee.
Damn... RIP Stan. Thanks for everything. pic.twitter.com/TMAaDJSOhh— Ryan Reynolds (@VancityReynolds) November 12, 2018
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!!— Chris Evans (@ChrisEvans) November 12, 2018
"There will never be another Stan Lee," said Evans. "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!!
We’ve lost a creative genius. Stan Lee was a pioneering force in the superhero universe. I’m proud to have been a small part of his legacy and .... to have helped bring one of his characters to life. #StanLee #Wolverine pic.twitter.com/iOdefi7iYz— Hugh Jackman (@RealHughJackman) November 12, 2018
"Stan Lee was a pioneering force in the superhero universe. I’m proud to have been a small part of his legacy and .... to have helped bring one of his characters to life," said actor Jackman, who played Wolverine in the Marvel X-men series.
Thank you Stan Lee for making people who feel different realize they are special.— Seth Rogen (@Sethrogen) November 12, 2018
Lee's daughter JC Lee confirmed he died after being taken to hospital on Monday, aged 95.
"He felt an obligation to his fans to keep creating," she said in a statement.
Stan Lee, RIP. Thanks for inspiring so many of us to pick up a pen or pencil and put your dreams onto paper. Excelsior! pic.twitter.com/L33eTjUQdI— edgarwright (@edgarwright) November 12, 2018
"He loved his life and he loved what he did for a living. His family loved him and his fans loved him. He was irreplaceable."
His trademark slogan "Excelsior!" started in the '60s when Lee wrote a monthly column called Stan's Soapbox, in Marvel's Bullpen Bulletins. He ended every column with the heroic motif, and said it had since just become a catchphrase.
Actress Jamie Chung posted on Twitter that it was "an honour" to work with the comic book superstar.
Lee, who was known for making numerous cameo appearances in the Marvel Cinematic Universe, was a writer, editor and publisher at Marvel.
He also created or co-created Iron Man, Thor, the Fantastic Four, Black Panther, Daredevil and Ant-Man, as well as numerous other characters which shot to mainstream stardom as Marvel series' were rebooted for numerous movie franchises in recent years.
Representatives from Marvel's long-time rival in the comics world, DC, which created Batman and Superman, also paid their respects to the writer who "changed the way we look at heroes."
He changed the way we look at heroes, and modern comics will always bear his indelible mark. His infectious enthusiasm reminded us why we all fell in love with these stories in the first place. Excelsior, Stan.— DC (@DCComics) November 12, 2018
As a writer and editor, he was key to the ascension of Marvel into a comic book titan in the 1960s when, in collaboration with artists such as Jack Kirby and Steve Ditko, he created superheroes who would enthral generations of young readers.
Working with Kirby in 1961, Lee created the modern superhero with the invention of the Fantastic Four.
He went on to create characters including Spider-Man, Hulk, the X-Men and the Avengers with Kirby and Ditko.
I was first interviewed for Stan Lee's obituary about 20 years ago. I was happy he defied the reaper and carried on. With Stan gone, an era really does come to an end. He was the happy huckster that comics needed. And he really did alliterate like that when you talked to him.— Neil Gaiman (@neilhimself) November 12, 2018
Fellow comic book giants also paid their respects to their "hero", including Neil Gaiman and Sin City creator Frank Miller.
Devastated by my pal Stan's passing. He was a childhood inspiration, an instructor to me when I was just getting started and a genuinely sweet man. Will miss him terribly.— Frank Miller (@FrankMillerInk) November 12, 2018
"I was first interviewed for Stan Lee's obituary about 20 years ago," said Gaiman, who wrote the Sandman series and various issues for DC and Marvel. "I was happy he defied the reaper and carried on. With Stan gone, an era really does come to an end."
Rest in peace, Stan Lee. The many worlds of imagination & delight you created for humanity will last forever.— Elon Musk (@elonmusk) November 12, 2018
The last 18 months had been turbulent for Lee and he lost his wife Joan in July last year after 69 years of marriage. A series of health scares followed.
Lee had tweeted yesterday to honour fallen troops for America's Veterans Day.