Weirdworld was a fantasy series created by Doug Moench and Mike Ploog for American company Marvel Comics, set in a dimension of magic. A comic book series titled Weirdworld debuted in 2015 as a tie-in to the Secret Wars storyline, followed by a six-issue series as a part of the All-New, All-Different Marvel branding.

Originally intended to be published in the discontinued Monsters Unleashed, the first "Weirdworld" story eventually appeared in the one and only issue of the black-and-white magazine Marvel Super Action. It then was featured in the color comic book Marvel Premiere #38 (October 1977). In late 1977 or early 1978, co-creator Ploog left Marvel in a contract dispute while in the midst of drawing a 60-page "Weirdworld" story, written by Moench, that the company had planned to publish as one of its Marvel Comics Super Special series of one-shots. Ploog recalled in 1998 that he had "a disagreement with [editor-in-chief] Jim Shooter. I had moved to a farm in Minnesota, and agreed to do a hand-colored 'Weirdworld' story. Marvel backed out of the deal after I had started. I can't remember the details, but it doesn't matter. I think I was ready to move on. Marvel and I were both changing". Rick Marschall, the story's editor, said in 1978 that Ploog had been given four months to complete the art, and when it became evident that the deadline would not be met, arranged to publish the story in two 30-page installments, giving Ploog two more months. Ploog sent Marvel photocopies of the first 31 pages, and was paid for them. During this time, Marvel had given work-for-hire contracts to its freelancers, many of whom, including Ploog, refused to sign, resulting in cessation of work for Marvel. Ploog "took himself off the project", said Marschall, and retained his original artwork. Moench's script was eventually published as a 106-page story illustrated by penciler John Buscema, inker Rudy Nebres, and airbrush colorist Peter Ledger as the three-part "Warriors of the Shadow Realm" in Marvel Super Special #11–13 (Spring–Fall 1979). Additional Weirdworld stories were published in several issues of Epic Illustrated in 1981 and 1982.

Ploog's unused 1978 pages were reworked into the first part of a "Weirdworld" trilogy, in Marvel Fanfare #24 (January 1986), with Pat Broderick penciling the two subsequent issues.

The protagonists were the Elves Tyndall and Velanna, both from the floating ring-shaped island of Klarn, and an irascible Dwarf dubbed Mud-Butt because he tended to land on his backside in a quarrel.

As part of the 2015 Secret Wars storyline, a miniseries titled Weirdworld starring Arkon was released in June which featured other characters like Morgan le Fay of Earth-15238, Skull the Slayer, a variation of Jennifer Kale from Earth-11234 that is the Queen of Weirdworld's Man-Things, and characters from The Saga of Crystar. Weirdworld is featured on the map of the storyline's version of Battleworld as a floating island composed of fragments from many alternate reality magical realms like Polemachus, Crystalium, Klarn, and the original Weirdworld. By the end of the miniseries, Weirdworld manifested on Earth-616 in the Bermuda Triangle.

Weirdworld remained as part of the Marvel Universe post-Secret Wars and became the setting of a new volume of Weirdworld.

Rebecca "Becca" Rodriguez was an American teenager who was flying from the United States of America to Mexico on board Flight 789. While traveling through the Bermuda Triangle, the Boeing 747 crashed into Weirdworld where its surviving occupants were rescued by Arkon. Rebecca encountered the Ogeode who stated that he caused the plane to crash with the artefact called the Wuxian Seed. Ogeode was then killed by Goleta the Wizardslayer and the Wuxian Seed falling into Rebecca's possession. Alone in Weirdworld, Rebecca agreed to become Goleta's squire and the two set off together, unknowingly being tracked by the Catbeast that had emerged from Ogeode's corpse. While traveling around Weirdworld, Rebecca and Goleta are startled by the Catbeast's sudden appearance and drove off the road. Upon reaching safety, the Catbeast caught up to them and revealed himself to be Ogeode. This forces Becca to step between him and Goleta's axe lest he be killed again before he could send her back to Earth. Ogeode's Catbeast form then explains to get Rebecca back to Earth, they need to travel across the Fang Mountains to retrieve a spare wizard body. Rebecca met Eta the Watcher who urged her not to go to the Fang Mountains or else it would bring a full scale war to all of Weirdworld.

Weirdworld is also the setting for a new series starring Dane Whitman, the Black Knight. Black Knight fled to Weirdworld after using the Ebony Blade to kill Carnivore. Upon arriving on Weirdworld, he killed King Zaltin Tar to establish New Avalon and built an army with the help of Shield and Spear. Black Knight has the army built in anticipation of the arrival of the Avengers Unity Division who are seeking to bring him to justice.