Simon's family relayed word of his death Thursday, posting a short statement on Facebook and telling The Associated Press through a spokesman that Simon died Wednesday night in New York City after a brief illness.
"Joe was one of a kind," said Steve Saffel, of Titan Books, a Simon friend who worked with him on his recent autobiography, "Joe Simon, My Life In Comics."
Saffel said that Simon, born in Rochester, N.Y., in 1913, "lived life on his terms and created incredible things in the process. It was a privilege to know him and to call him my friend."
Among Simon's creations was a partnership with Kirby, a comic book artist and illustrator. The duo worked hand-in-glove for years and from their fertile imaginations sprang a trove of characters, heroes, villains and misfits for several comic book companies in their Golden Age of the 1940s, including Timely, the forerunner of today's Marvel Comics; National Periodicals, the forerunner of DC; and Fawcett, among others.
The characters the two created included the Newsboy Legion, the Boy Commandos and scores more, such as Blue Bolt.
"Blue Bolt was the first strip Jack and I worked on together, beginning in 1940. He was a science fiction swashbuckler I created for Curtis Publishing, the company that put out the Saturday Evening Post," Simon told the AP earlier this year. "They had decided to jump on the comic book bandwagon. Jack joined me with the second issue. Like Captain America, Blue Bolt got his powers from an injection, long before the baseball players were doing it."
For Timely, the duo created Captain America, debuting on the cover of "Captain America Comics" No. 1 with the champion of liberty throwing a solid right-hook at Adolf Hitler in December 1940, a year before the United States entered World War II.
"Jack and I read the newspapers and knew what was going on over in Europe. And there he was - Adolf Hitler, with his ridiculous moustache, high-pitched ranting and goose-stepping followers. He was the perfect bad guy, much better than anything we could have made up, so what we needed was to create his ultimate counterpart," Simon told the AP.
"Cap is one of the great comic book icons, and as dangerous as the world is today - more than it was in the 1940s - we need him around more than ever to act as our moral compass," Simon said.
Ed Brubaker, whose recent runs writing Captain America for Marvel have been heaped with critical acclaim, called Simon a "pioneer in comics, a mover-and-shaker and probably far ahead of his time."
He said in an email that he even revamped a Simon-created character for his first assignment at DC.
"I personally owe my career in a few ways to Joe Simon - my first DC gig was a revamp of his `Prez,' the teenage president, and I've spent almost eight years writing Captain America for Marvel," Brubaker said. "It's a sad day."
Simon wrote "Prez: First Teen President" for DC in 1973-74 as a four-issue series.
Mark Evanier, a comic industry historian and Kirby biographer, noted that Simon, besides being able to write and draw, also knew how to edit comics.
"Joe himself was the first great real editor who brought to comics skills he'd learned elsewhere and had some perception of how to put a magazine together and how to make a professional looking publication," Evanier said Thursday. "He had some business acumen. He knew how to talk to publishers, he knew how to make deals."
He also knew the market, Evanier said, noting that Simon, along with Kirby, plunged head first into creating horror, crime, humor and romance comics in the aftermath of World War II.
Simon said earlier this year that creating the romance comics was a high point for him and Kirby because they "negotiated to own half of the property," something that had been an uncertain prospect in the industry.
"I'd like to think that we showed today's comic book writers and artists how they can do more than just make a living producing comic books and hold onto the fruits of their labors," he said.
Simon is survived by two sons, three daughters and eight grandchildren.