Robert Downey Jr.
"I owe it all to you," the Iron Man actor wrote on Instagram. "Rest in peace, Stan."
Chris Evans
"There will never be another Stan Lee," tweeted Evans, who began playing Captain America in 2011. "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!!"
Scarlett Johansson
"The galaxy just gained another Dog Star," the actress, who plays Black Widow in multiple films, told E! News in a statement. "Thankful everyday to be a small part of Stan's universe. He was a legendary visionary and a true artist."
Ryan Reynolds
"Damn...RIP Stan," the Deadpool actor wrote on Instagram. "Thanks for everything."
Halle Berry
"RIP, Stan Lee. Thank you for sharing your incredible vision with us. We are eternally grateful to you and would not be the same without it," tweeted Berry, who played Storm in three X-Men movies. "I am so honored to have played a part in your world and will forever look back on the opportunity with love."
Hugh Jackman
"We've lost a creative genius. Stan Lee was a pioneering force in the superhero universe," Jackman, who began playing X-Men's Wolverine in 2000, wrote on Instagram. "I'm proud to have been a small part of his legacy and to have helped bring one of his characters to life."
Paul Bettany
"Now that was a life well lived and lived to its fullest. Excelsior! 1922-2018," the actor, who played Vision in multiple films, wrote on Instagram. "Thank you Stan Lee, from all your fans."
Zoe Saldana
"Today we lost one of the greats. Stan Lee, you were an inspiration and superhero to us all," the actress, who played Gamora in the Guardians of the Galaxy films, wrote on Instagram. "Thank you for contributing so much- and giving us all something to aspire to!"
Chris Hemsworth
"RIP my friend. Thank you for the incredible adventures your stories took all of us on," Hemsworth, who played Thor, tweeted. "My love and support goes out to all your friends and family."
Joss Whedon
"Stan Lee created a universe where, if a character was beloved enough, they could never really die. Now THAT'S thinking ahead," the Avengers and Avengers: Age of Ultron director tweeted. "Thanks for so much of my life. You'll never not be in it."
Don Cheadle
"On set right now and just heard the news. Stan gave us so much joy, and not just as an exceptional storyteller and artist, but also through his work with his foundation," the actor, who plays War Machine, tells E! news. "His 'Tony Stank' line will live with us forever. Rest in power, friend."
Evangeline Lilly
"Stan...more than a master of stories, you always seemed like a master of living," the star of Ant-Man and the Wasp wrote on Instagram. "I will look to you for inspiration for the rest of my life. You live on. xoxo Your Wasp."
Chris Pratt
"Thanks for everything Stan Lee! What a life, so well lived," Pratt, who played Star-Lord in Guardians of the Galaxy, wrote on Twitter. "I consider myself extraordinarily lucky to have gotten to meet you and to have played in the world you created."
Lupita Nyong'o
"I am saddened to learn about the passing of Stan Lee. From watching Marvel films with my friends in college to having the privilege to take on one of his characters in Black Panther, Stan's creative genius sparked my imagination and left me in awe," the actress, who played Nakia, wrote on Instagram. "His legacy will carry on in all of us who relish in the worlds he created. Worlds that renew our spirits and help us cope with our own."
Josh Brolin
"Stan Lee and Dr. Seuss and Ray Bradbury. That's where it begins and ends with me," Brolin, who played both Cable and Thanos onscreen, wrote on Instagram. "To those of us who have been so deeply affected by the humanity of his imagination, the understanding of reaching beyond our potential and the necessity of tapping into our immeasurable imaginations, we thank you and are forever indebted. Rest in peace, dear Stan. You made our time here a better one."
Rebecca Romijn
"He was a friend. When we were afraid, he gave us strength. When we were alone, he gave us a family," the actress, who played Mystique in the X-Men films, tweeted. "He may be gone, but his teachings live on through us, his students. Wherever we may go, we must carry on his vision. And that is a vision of a world united. RIP Stan Lee."
Sebastian Stan
"Thank you great legend. You will be missed," Stan, who plays Winter Soldier, wrote on Instagram. "I wouldn't be here without you."
Chloe Bennet
"Sweet, sweet Stan. You gave people all around the world something to believe in. Something bigger than themselves," Bennet, who plays Quake on Marvel's Agents of S.H.I.E.L.D., wrote on Instagram. "You taught us that you don't need to have powers to be super. That a big heart and kindness can change the world. You made everyone around you come to life with laughter and joy. I will miss the giggles. Thank you for all you have given us, you will be missed. RIP."
Mark Ruffalo
"Sad, sad day. Rest in power, Uncle Stan. You have made the world a better place through the power of modern mythology and your love of this messy business of being human. You let us be extra human...superhuman even," the actor, who played The Hulk in multiple movies, wrote on Instagram. "I am deeply honored to have been a small part in the Stan Lee constellation."
Gwyneth Paltrow
"I just heard about Stan Lee. He will be so missed," the actress, who played Pepper Potts in the Iron Man movies, wrote on Instagram. "What a genius, and always so lovely. True gentleman."
Tom Holland
"How many millions of us are indebted to this guy? None more so than me. The father of Marvel has made so many people so incredibly happy," said Holland, who is the third actor to play Spider-Man on the big screen. "What a life and what a thing to have achieved. Rest in peace, Stan."
Hayley Atwell
"You were always so kind and enthusiastic and a delight to be around," said Atwell, who played Agent Peggy Carter. "Thank you, Stan. For all these much loved characters."
Doug Jones
"What can I say about the loss of a visionary who created one of my favorite characters I've ever played? Like a lot of us, I just figured Stan Lee would live forever, yet his fun loving wit, charm, and poetic legacy lives on for generations to come," Jones, who starred in Fantastic Four: Rise of the Sivler Surfer, wrote on Instagram. "My heart hurts, and he will be sorely missed."
Kat Dennings
"Stan Lee. A gentleman and a genius," tweeted Dennings, who played Darcy Lewis in the Thor films. "It was an honor to be a small part of his universe. Rest in peace."