Gerry Conway, a renowned comic book writer who helped create characters and stories for Marvel and DC, including the Punisher character in the Spider-Man comics, has died aged 73.

In a statement announcing his death, Marvel described Conway as a legendary comic book writer with a prolific career.

He died of pancreatic cancer on Sunday in Thousand Oaks, California, his wife, Laura Conway, told The Associated Press.

"From Spider-Man to the Avengers, Iron Man to Captain Marvel, Gerry Conway has deftly written almost every character in the Marvel Universe," Marvel Comics Editor-in-Chief C.B. Cebulski said.

"Gerry Conway's legacy has made an undeniable and indelible impact on the Super Hero stories we know and love. He will be dearly missed."

Tributes were also shared on social media.

"While many know his Marvel accomplishments ... Gerry's contributions to DC were equally impactful and significant: shaping Batman, Superman, the Justice League of America, and co-creating Firestorm, Jason Todd and Power Girl and so many more," Jim Lee, chief creative officer and president of DC Comics, said in an Instagram post.

"Thank you, Gerry, for the worlds imagined and the heroes created."

Conway was born in Brooklyn on September 10, 1952. He started writing comic book stories as a teenager, and by the age of 19 he landed work on The Amazing Spider-Man - which Marvel's statement described as "the job that would change his life - and the comic book industry at large - forever."

Conway's writing featured "pivotal moments" that redefined the series, Marvel said, such as the death of Gwen Stacy, Peter Parker's girlfriend. He also co-created the Punisher, a vigilante antihero known for the skull logo on his chest.

Conway had a way of imbuing characters with nuance and emotional depth, Marvel said.

Beyond the Spider-Man comics, Conway wrote for several other major Marvel titles, including Fantastic Four, Thor and The Incredible Hulk.

In a 1981 interview with The Comics Journal, Conway noted how comic books can appeal to both younger and older audiences.

"I'm writing for the youthful part of myself, the primitive part of myself," he told the magazine.

"If an adult likes the books it's because of a nostalgic feeling for that primitive, easy conceptualisation of heroic purpose."

Conway loved meeting fans, his wife Laura said.

At his last public comic book signing in February, "he was tired and in a lot of pain as the cancer was spreading, but he stayed an extra two hours to make sure every fan in line could get their book signed and have a moment to talk with him about comics," she said.

"That's the kind of person he was."

Conway is survived by his wife and two daughters from previous marriages.