R.I.P. Len Wein, co-creator of Wolverine and Swamp Thing

As confirmed in a tweet from DC Comics, highly influential comic book writer and editor Len Wein has died. A cause of death has not been given. Wein was 69.

Born in New York City in 1948, Wein says he was a “sickly kid” and he would often read comic books to keep himself occupied. He shared this interest with his good friend Marv Wolfman, who would also go on to become an influential figure in the comic book world. The two of them essentially forced their way into DC Comics in the ‘60s, where they became freelance writers. From there, Wein’s star continued to rise, with DC Entertainment president Diane Nelson noting in a statement that “there’s hardly a facet of DC’s world that Len didn’t touch” and that he “wrote or edited almost every major DC character” over the years.

At DC, Wein co-created the iconic horror character Swamp Thing with artist Bernie Wrightson—who also died earlier this year. Some of his stories laid the groundwork for decades of threads that other well-regarded writers (including Grant Morrison and Alan Moore) would pick up on over the years, and he even came up with an important piece of the puzzle for Christopher Nolan’s Dark Knight movies by creating Lucious Fox. In the ‘70s, he began writing for Marvel Comics and co-created a character with a significantly larger impact: Wolverine.

Wein and artist Dave Cockrum resurrected the X-Men series in 1975, adding a number of new characters to the team (including Wolverine, Nightcrawler, and Storm). He also—once again—laid the groundwork for the book to evolve into something bigger and deeper, specifically when Chris Claremont came on board and helped make the X-Men into the huge series it is now. By the end of the decade, though, a dispute resulted in Wein leaving Marvel for DC. At this time, Wein worked as an editor for a number of DC books, including his old friend Marv Wolfman’s New Teen Titans and—perhaps more importantly—Alan Moore and Dave Gibbons’ Watchmen.

Multiple figures in the comic book industry have offered tributes to Wein on Twitter: