Lee is known for co-creating characters like Black Panther, Spider-Man, X-Men, Thor, Iron Man, the Fantastic Four, the Incredible Hulk, Daredevil, and Ant-Man.
After hearing about his death, big names including Chris Evans and Robert Downey Jr. mourned his loss on social media.
Chris tweeted, "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!!"
Robert wrote on Instagram, "I owe it all to you,,, Rest In Peace Stan... #MCU #Excelsior #legend #rip #stanlee #TeamStark
No one has had more of an impact on my career and everything we do at Marvel Studios than Stan Lee. Stan leaves an extraordinary legacy that will outlive us all. Our thoughts are with his daughter, his family, and his millions of fans. #ThankYouStan #Excelsior!