Stan Lee, founder of Marvel Entertainment Inc., poses for a photograph with a life size model of his superhero Spider-Man while in his office in Beverly Hills, California, U.S., on Thursday, Dec. 18, 2008.

In an essay remembering Lee posted Monday afternoon, Marvel and Disney said they "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."

All of those characters have since been adapted into hugely popular, budget-busting films, most of which were made after entertainment giant Disney bought Marvel for $4 billion in 2009 .

Lee was the creator of dozens of now-iconic comic-book heroes, including Spider-Man, X-Men, the Avengers, the Fantastic Four and Black Panther.

Stan Lee, one of the masterminds of the Marvel Comics universe, has died at 95 .

Robert Iger, Disney chairman and CEO, said in the essay that "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."

Lee's work creating characters for Marvel spanned the 1960s and into the early 1970s. But Lee was still involved with the production of the films based on his comics, and regularly made brief, tongue-in-cheek cameos within the movies.

He became known for imbuing in his heroes the sort of flaws that were rarely visible among other comic-book protagonists, such as jealousy, pride and even financial constraints.

His voice often extended beyond the comic panel, as well, notably in his monthly "Stan's Soapbox" column.

Tweet soapbox

Lee was also a World War II veteran, having served in the signal corps. His official Twitter account's last post commemorated Veterans Day.

Lee tweet

Tesla co-founder and CEO Elon Musk, who has mentioned his interest in visual arts in the past, also paid tribute to Lee.

Musk tweet

Asked on CNBC in 2014 if comic-book films were over-saturating Hollywood, Lee said, "Oh, I don't think it's enough."

"I think that they'll just go on as long as we come up with good stories for them," he added.