Stan Lee, the Marvel Comics visionary who co-created several of the brand's most iconic superheroes, including Spider-Man and The Incredible Hulk, has died at the age of 95.

Lee died at Los Angeles' Cedars-Sinai Medical Center early Monday morning after being rushed there via ambulance. Lee, who had been active and fond of public appearances up until recently, had been in declining health for about a year, suffering from vision issues and a bout of pneumonia.

Along with artist Jack Kirby, Lee revolutionized Marvel Comics in the early 1960s with the launch of popular super squad The Fantastic Four. Lee and Kirby's fruitful collaboration also lead to the creation of Iron Man, Thor and the X-Men. Lee's groundbreaking depictions of superheroes changed the landscape of comics, paving the way for an empire that would include some of the most commercially successful movies ever made, TV series across multiple networks, and a massively profitable merchandising arm.

Born Stanley Martin Lieber on Dec. 28, 1922, the native of the New York City neighborhood Washington Heights took the pen name Stan Lee around 1941 while working at Timely Comics, which would eventually evolve into Marvel comics. At age 19, he was named interim editor, and then, after serving in the second World War, he returned and became the editor for the launch of their blockbuster superhero series The Fantastic Four. Other big characters including The Incredible Hulk, Spider-Man, and X-Men followed, and Lee and Kirby eventually grew Marvel into the world's No. 1 publisher of comic books. Lee became publisher in 1972 and came to Los Angeles in 1980 to make inroads into Hollywood.

Marvel, of course, has become a multimedia powerhouse and was purchased by the Walt Disney Co. in 2009 for $4 billion. Lee's superhero characters have not only become pop culture institutions but also huge money-making enterprises at the box office. The Avengers and Black Panther, for example, are two of the top-grossing superhero films of all time.

Dozens of Marvel characters have also gone on to dominate television, including live action shows Jessica Jones, Luke Cage, Marvel's Runaways and Daredevil along with scores of animated shows, including several Avengers properties. While the shows sometimes drew the ire of passionate fans who took issue with the adaptations' diversion from comic book canon, Marvel's series earned critical praise and popular devotion for the way they tackled socio-political topics like racism, women's rights, social justice and plain old good-versus-evil.

Lee, who was famous for making cameos in movies and shows based on characters he created, was known as a vivacious character, but in recent years, his personal life began to make headlines. Earlier this year, Lee was reportedly accused of sexual harassment by employees of a nursing company (claims he denied via his attorney). He sued executives at POW! Entertainment, a company he founded to develop TV, film and game projects, for $1 billion in 2017, accusing them of fraud and then dropped the suit weeks later; he sued an ex-business manager soon after, and in June of 2018, he was part of an investigation into elder abuse by his own daughter.

He's survived by his daughter, J.C., and younger brother, Larry Lieber, who is a Marvel writer and artist. His wife of 69 years, Joan, died in 2017.