The omnibus launched three years after Marvel released its first oversized hardcover (or OHC). With the lines running side-by-side while sharing the same print size, there was often confusion in regards to how Marvel classified books. In 2015, a Spider-Verse 'oversized hardcover' was released at 648 pages;^[5] yet, months later, a Superior Foes Of Spider-Man 'omnibus' came out, with only 376 pages.^[6] Both collected full runs of a Spider-Man miniseries that had been released within the prior two years. In February 2019, the Hulk: Dogs Of War 'oversized hardcover' was 832 pages; while, four months later, Hulk by Loeb and McGuinness was a 912-page 'omnibus'.^[7][8]

The contents of an OHC and omnibus may be identical: The 2011 'oversized hardcover' of X-Men: Fall Of The Mutants was re-released with the exact same page count and cover in 2022, while using 'omnibus' branding. Similarly, 2025's X-Men: Fatal Attractions 'omnibus' has the same content to the 2012 'oversized hardcover'.^{[9][10][11][12]}

The smallest omnibus was 2007's Devil Dinosaur at 184 pages, while the largest oversized hardcover was 2013's Avengers vs. X-Men Companion at 1,112 pages.^[13][14]

The practice of having multiple covers for the same comic book has been a feature of the industry since the mid-1980s.^[15] This increased throughout the 1990s, with the five covers for 1991's X-Men #1 helping it to sell a record-breaking 8.1 million copies.^[16]

Marvel omnibuses have used variants since the first release of Fantastic Four Vol. 1 in 2005. The main 'bookshop' cover featured the original artwork from Fantastic Four #1, drawn by Jack Kirby; with a 'variant' version of the same image produced by Alex Ross. Variant covers are exclusive for the direct market, meaning they are only available from comic book shops, or specialist retailers.

The practice is polarising, being described as both "exciting options for readers who want a different flavor from what they're buying", but leading to comics companies avoiding "finding new readers... by selling more to existing ones".^[17][18]

The vast majority of Marvel omnibuses released between 2005 and September 2016 had a variant. The practice largely disappeared until early 2020, although, by 2021, every new Marvel omnibus again had more than one cover.

Marvel's Senior Vice President of Sales & Marketing, David Gabriel, said: "As long as no one is just taking advantage of customers and retailers, I think it [the production of variant covers] is going to continue to grow for a while."^[19]

These books contain stories that take place in the primary Marvel Universe. This fictional continuity is often referred to as Earth-616, with a legacy that stretches back to 1939.^[20]

Jim Starlin's interpretation of Adam Warlock was named by Publishers Weekly as one of Marvel's 10 hidden gems. The 1975 to 1977 portion of the Adam Warlock omnibus "is a heady, trippy sci-fi epic about what happens when a lab-created 'perfect man' discovers that the evil messiah of the cruel intergalactic church he's been battling is, in fact, his own future self." The omnibus also contains the introduction of infinity gems and Gamora.^[21]

The all-Canadian team of Alpha Flight was first introduced in Uncanny X-Men #120, by writer Chris Claremont and artist/co-plotter John Byrne. The debut led to the spin-off series, with Byrne writing and drawing the first 28 issues - all of which is collected in the Alpha Flight by John Byrne omnibus.^[22]

Jed MacKay's Black Cat omnibus contains the complete series. The story spun out of Amazing Spider-Man (vol. 5) #16, where the character crossed the Thieves Guild, "leading her to go on the run both from the secret order as well as the authorities."

That issue is collected in Amazing Spider-Man by Nick Spencer Omnibus Vol. 1.^[23]

• See also: Daredevil collected editions

Marvel Comics held the rights to publish Godzilla comics for two years from 1977. The series ended after 24 monthly issues, when copyright holder Toho "asked for a large increase to its license fee after the first year of the series, and an even larger increase after the second year".^[24] In 2024, "thanks to an exciting new collaboration with Toho International", Marvel released the full run in a single omnibus.^[25]

Even though Godzilla is licensed, S.H.I.E.L.D. play a large part throughout the series, with Fantastic Four and The Avengers appearing from issue #20.

Brian Michael Bendis wrote the entirety of the Alias series, which introduced the character of Jessica Jones to the Marvel Universe. The character "eschews costumes, works and plays hard, and opens up a set of detective stories unlike any the comics had seen before. Bendis provided a character with real heart and a unique point of view, and it's one that has broadened Marvel's horizons across mediums."^[26]

The Alias omnibus came out in March 2006. It was the second Marvel omnibus to be released overall, and the third reprint - in 2021 - was re-titled Jessica Jones: Alias.

Based on a Mego Corporation toy line, the Micronauts comics were produced by Marvel between 1979 and 1986. Marvel re-acquired the publishing rights in 2023.^[27]

Miles Morales is a half-Black, half-Hispanic teenager and was created by Brian Michael Bendis. The character first appeared in Ultimate Comics: Fallout #4.^[28]

Bendis told USA Today that he was inspired in part by Donald Glover's appearance in the TV series Community dressed as Spider-Man. Bendis said: "[Glover] looked fantastic! I saw him in the costume and thought, 'I would like to read that book.' So I was glad I was writing that book."^[29]

• See also: Miles Morales collected editions