DALLAS, TX.- One of three known copies of the most important comics book in the medium's history serves as the centerpiece of Heritage Auction's April 1-4 Comics & Comic Art Signature event: an ashcan copy of Action Comics No. 1 from 1937. It's also the best-known copy in existence. And until now, it has never been for sale to the public.

It's not hyperbole to say this is the mock-up that changed history, the prototype that shaped an industry. After all, this is the very book to feature the words "Action Comics" and the logo still used by DC Comics 84 years after this exemplar was made. The artwork, by The Shadow and pre-Batman Detective Comics illustrator Craig Flessel, may look unfamiliar; this blade-wielding ghoul, rejected for the cover of Detective No. 2, is no car-tossing Superman, after all. But the template had been set; the die, forever cast.

This is Action Comics before Action Comics. And everything that came after.

From its inception in the late 1930s through the 1950s, DC Comics frequently made these so-called ashcans — mock-up covers bound over the interiors of existing books — to establish trademarks, to keep the competition from stealing titles and logos and even heroes. The ashcans, so-called, allegedly, because they were intended to be tossed and destroyed, were then distributed across state lines and sent to the U.S. Trademark and Patent Office, which made legal the publisher's claims to title.

For Action Comics DC publisher Harry Donenfeld had three ashcans made featuring variations on the title: Action Comics, Action Funnies and Double Action Comics. The latter offerings "were for spin-offs that never happened," according to the deluxe edition of DC's 2018 Action Comics: 80 Years of Superman.

The very logo used on this Action Comics ashcan is the one still on file with the U.S. Trademark and Patent Office, which received DC's submission on Jan. 28, 1938. The comics publisher told the patent office that Action Comics had first been used "in commerce" on Dec. 1, 1937 — which means this ashcan predates Superman's first flight by at least five months.

Of the three known copies, one is locked away in DC Comics' vault, seldom to be seen and never to be sold. Another copy, graded CGC 9.0, changed hands 11 years ago.

The Action ashcan being offered by Heritage, graded CGC NM- 9.2, is the highest-graded copy in existence.

And its provenance is impeccable.

This pre-action Action Comics No. 1 come from the collection of The Overstreet Comic Book Price Guide ashcan advisor and comic book historian Gary Colabuono, whose ashcan collection was so revered that a decade ago it was displayed at Chicago Comic Con and written about in the Chicago Tribune.

"When you see them, they are so cool," Colabuono told the newspaper. "They shouldn't exist. They should be gone. They're like pop culture relics or artifacts."

Added the convention's organizer, former Wizard Entertainment CEO Gareb Shamus, "When you talk about collectibles, it's all about having things that are rare and, in a lot of cases, one-of-a kind. What Gary has is a piece of history that people haven't seen before. That's what gets the juices flowing for collectors out there."

Colabuono bought his Action Comics ashcan, along with the one for Action Funnies, in 1986 — from none other than Sol Harrison, who in 1933 worked on Famous Funnies (considered the first comic book) and wound up becoming DC's president 43 years later.

This is the first time the book has ever been offered for sale. And it might just be the last time.