Steinberg as she appeared in Marvel What If #11. Art by Jack Kirby.

Flo Steinberg, one of the earliest Marvel employees and an American indie comics icon, has passed away. When Marvel Comics began, she and Stan Lee were the company’s first and only employees; as Lee’s secretary and assistant, she responded to fan mail, helped manage Marvel’s small offices with Lee, and ran the Merry Marvel Marching Society, Marvel’s first fan club, and saw the company transform into the pop culture icon it is today from the ground up.

Steinberg ultimately moved on from Marvel in 1968, but she was forever immortalized in the pages of the company’s work, not just through her fan mail responses but even as a co-star in Marvel What If #11. The tale imagined the original Marvel “bullpen” of office workers—Steinberg, Lee, Sol Brodsky, and Jack Kirby—transformed into the Fantastic Four, with Flo taking on the role of the Invisible Woman: a “fit projection of Flo Steinberg’s courageous dedication to a venture filled with countless dangers,” as Kirby wrote.

After she left Marvel, Steinberg went on to make more comics history: in 1975 she went on to publish Big Apple Comix, one of the first American indie comics. Steinberg would later return to Marvel as a proofreader in the ‘90s, and was still occasionally proofreading comics for the company up until recently, according to Ryan Penagos, vice-president and executive editor of Marvel’s digiaal media.

Here’s a brief statement Marvel released on her passing:

We are incredibly saddened to hear of Flo Steinberg’s passing and send our deepest condolences to her friends and family. Flo has always been the heart of Marvel and a legend in her own right. She will be forever missed and always loved by all of us here at Marvel.

Our thoughts go out to her family, friends, and colleagues at Marvel.

[Marvel]