Stan Lee, the co-creator of Marvel Comics, has died aged 95.
The Associated Press said that a family lawyer had confirmed the death of the creator of Spider-Man, The Fantastic Four and The Incredible Hulk.
Celebrity news website TMZ said the 95-year-old was rushed to hospital from his Hollywood Hills home on Monday morning.
It said Mr Lee's daughter confirmed her father had later died at the Cedars-Sinai Medical Centre.
Mr Lee, who recently fought off a bought of pneumonia, founded Marvel Comics with Jack Kirby in 1961.
— Marvel Entertainment (@Marvel) November 12, 2018
Marvel paid tribute to Lee, calling him the "creator, voice and champion" of the company.
A statement on their website says: "Today, Marvel Comics and The Walt Disney Company pause and reflect with great sadness on the passing of Marvel Chairman Emeritus, Stan Lee.
"With a heavy heart, we share our deepest condolences with his daughter and brother, and we honor and remember the creator, voice and champion of Marvel."
It added: "Marvel and the entire The Walt Disney Company salute the life and career of Stan Lee and offer their undying gratitude for his unmatchable accomplishments within their halls. Every time you open a Marvel comic, Stan will be there."
Bob Iger, chairman and chief executive of The Walt Disney Company, which owns Marvel, said: "Stan Lee was as extraordinary as the characters he created. A super hero in his own right to Marvel fans around the world, Stan had the power to inspire, to entertain, and to connect.
"The scale of his imagination was only exceeded by the size of his heart."
Mr Lee was born on December 28 1922 in Manhattan and grew up with a love of adventure books and Errol Flynn movies.
He started in the entertainment industry in 1939 and created or co-created Black Panther, Spider-Man, X-Men, The Mighty Thor, Iron Man, The Fantastic Four, The Incredible Hulk, Daredevil and Ant-Man among others.
Many of the characters' stories have since been turned into Hollywood films, turning the Marvel brand into a multibillion dollar business.
Mr Lee was renowned for making brief comical cameos in each of the Marvel universe films.
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
Tributes poured in, with director Edgar Wright, who was executive producer on the Antman film, saying: "Stan Lee, RIP. Thanks for inspiring so many of us to pick up a pen or pencil and put your dreams onto paper. Excelsior!"
Rest in peace, Stan Lee. The many worlds of imagination & delight you created for humanity will last forever.
— Elon Musk (@elonmusk) November 12, 2018
Billionaire entrepreneur Elon Musk wrote: "Rest in peace, Stan Lee. The many worlds of imagination & delight you created for humanity will last forever."
Thank you Stan Lee for making people who feel different realize they are special.
— Seth Rogen (@Sethrogen) November 12, 2018
Actor Seth Rogen also said on Twitter: "Thank you Stan Lee for making people who feel different realize they are special."