NEW YORK, NY.- Kevin O’Neill, a comic book artist best known as a creator of the series Marshal Law, a graphically violent exploration of superheroes, and The League of Extraordinary Gentlemen, which united characters from across literature, died Nov. 3 in London. He was 69.

The cause was cancer, said Tony Bennett, a friend of O’Neill’s and the founder of Knockabout Comics in London, which publishes international editions of The League of Extraordinary Gentlemen.

O’Neill’s art style was one of a kind: highly detailed, somewhat exaggerated and capable of veering toward lurid. An early Green Lantern story he drew for DC Comics was rejected by the Comics Code Authority, which set the industry standards on what comics could depict. Although the aliens that O’Neill depicted were demonic, contorted and grotesque, the objection was not to any particular image, but to his entire style.

In a 2014 interview with the website Comic Book Resources, O’Neill said he found the experience bizarre. “I’d heard all these stories about it’s just little old ladies in a room reviewing pages and stamping the back,” he said, adding, “It’s a really regressive way of producing comics.”

The story, written by Alan Moore, was published in 1986 — without the authority’s seal of approval, which by 2011 was dropped by most publishers in favor of their own ratings systems.

A more fruitful collaboration with Moore began in 1999 with the introduction of the League of Extraordinary Gentlemen, a team of classic literary characters including Allan Quatermain, the Invisible Man, Dr. Jekyll and Mr. Hyde, Captain Nemo and Mina Murray, one of Dracula’s victims. The team was originally featured in a six-issue series, and there were several sequels through 2019.

The series also inspired a 2003 film starring Sean Connery as Quatermain. Reviewing the movie in The New York Times, Elvis Mitchell described it as listless and “neither gentle nor extraordinary.” But the creators of the comic book would have the last laugh.

“When the movie came out, all the reviews were universally terrible, but a large number of them said you should read the book,” said Scott Dunbier, who edited the original series. “Our sales skyrocketed.”

In a statement to the Times after O’Neill’s death, Moore said: “Nobody drew like Kevin O’Neill. When I was putting together my formative ideas for The League of Extraordinary Gentlemen in the lead-out groove of the last century, I quickly realized that nobody save Kevin was qualified to present such a dizzying range of characters, periods, situations and styles with the vitality and ingenuity that the narrative — a ridiculous mashup of all human fiction since classical antiquity — seemed to demand.”

Their collaboration on this series, Moore said, began what was perhaps the longest, happiest and most productive partnership of both men’s careers.

O’Neill was born Aug. 22, 1953, in southeast London. His father was a contractor, his mother a homemaker.

He took his first step into the comic book industry in 1969, when he was hired as an office assistant for Buster, a humor publication for children. He would move on to coloring comic reprints and creating his own fanzine. His career took a big leap forward when he began working as an artist and an editor on the science fiction comics anthology 2000 AD, which premiered in 1977.

One of O’Neill’s accomplishments at 2000 AD was to successfully lobby to get credits added to the stories. “This was a huge breakthrough,” said Dave Gibbons, co-creator with Moore of the series Watchmen and a friend of O’Neill’s, “because previously in British comics, they used to actually employ people to remove artist signatures, with this kind of lame excuse that it would spoil the mystery for the reader if they saw it was drawn by somebody.”

That was a romantic notion, but it was also a business tactic: Identifying the creators would most likely lead the writers and artists to demand more compensation.

Information on O’Neill’s survivors was not immediately available.

While at 2000 AD, O’Neill met Pat Mills, its founding editor. “Kevin already had a portfolio of real cool science fiction material,” Mills said. “In fact, I still have those physical pages. They show graphic scenes of future war.”

O’Neill and Mills would go on to create the popular series Nemesis the Warlock, about a fire-breathing alien demon — the hero — in battle against a fanatically religious human dictator. Another success came in 1987 with Marshal Law, set in San Futuro, a city built on the remains of San Francisco after an earthquake, about a government operative whose mission is to take down rogue superheroes. His initial case involves a serial killer and his possible ties to a superhero.

“Marshal Law is quite cruel to superheroes, but there is a little bit of affection where Kevin is concerned,” Mills said. He noted that O’Neill would often display his humor in graffiti and other panel details.

Moore also remarked on O’Neill’s sense of humor, which was evident in what proved to be their last phone conversation. Moore said he noted that the two had never had a disagreement in their decadeslong collaboration. O’Neill, he said, “agreed, pointing out that we’d never had sex either, and that he was immensely grateful for both these things.”

This article originally appeared in The New York Times.