As the Fantastic Four prepare themselves for their debut in the Marvel Cinematic Universe in July, they have been having a bigger presence in the overall comic book zeitgeist, and a major example of this will be first teased on Free Comic Book Day, as Dynamite will be releasing aGargoyles/Fantastic Four crossover special in October, with the project teased in Dynamite's offering for this year's Free Comic Book Day on May 3, Gargoyles: Demona #0.
Based on the classic 1990s animated series, Gargoyles was the first title in Dynamite's popular series of Disney-related comic books, and now Dynamite is celebrating the success of that series by having the Manhattan Clan of the Gargoyles team up with ANOTHER family, in this case, Marvel's most famous family, the Fantastic Four, in a special one-shot crossover issue in October, written by Gargoyles creator Greg Weisman, artist George Kambadais, and letterer Jeff Eckleberry, the original creative team on Dynamite's first Gargoyles series.

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What is the Gargoyles/Fantastic Four one-shot about?

In Dynamite's press release for the release, it explained the premise of the crossover:
Key members of the Manhattan Clan, including Goliath, Elisa Maza, Brooklyn, Katana and Nashville have been invited on a tour of one of the most impressive and technologically advanced buildings in their adopted home of New York City — the Baxter Building. Everything goes awry when a fearsome cast of foes from both mythos cross paths, including Coldsteel, the Gargoyle aka Yuri Topolov, and the deadly Annihilus.
Fans will get to enjoy Franklin and Valeria bonding with Gnash, at least until everything gets out of control. Then both families — including Mister Fantastic, Invisible Woman, the Thing, the Human Torch, Broadway and Angela — will have to team up, split into teams, and save the day across Manhattan, the Negative Zone, and beyond.
So far, covers for the project by Dynamite star artist Lucio Parrillo, Fantastic Four veteran Mark Bagley, and Gargoyles icon Amanda Conner have been announced, but surely more covers will be announced before the project is officially released this Fall.

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What does Greg Weisman have to say about the event?

Weisman, who, of course, has had a long history with Marvel, including The Spectacular Spider-Man cartoon, and the current Spectacular Spider-Men series he is writing for Marvel Comics, had this to say about the event, "This is a tale of clan and family," said writer Greg Weisman. "And it's a thrill to get this opportunity to bring the first family of the Marvel Universe together with the Manhattan Clan. It feels right!"
As noted, the whole event will kick-off in a backup preview in Gargoyles: Demona #0, and THAT series is notable because, as Dynamite notes, Weisman will be "joined by original series co-producer Frank Paur for a centuries-spanning look at the hero-turned-villainess' life — including never before revealed family members and pivotal moments. The full series will follow the FCBD release."
Gargoyles: Demona #0 is out on May 3, Free Comic Book Day.
Gargoyles/Fantastic Four will be out in October.
Source: Dynamite