"Fear Itself" began as a proposed Captain America/Thor crossover by Matt Fraction. The storyline was first announced by then-Marvel Editor-in-Chief Joe Quesada, Vice President Executive Editor Tom Brevoort and Vice President and X-Men group editor Axel Alonso in a December 21, 2010 press conference at Midtown Comics Times Square. Quesada explained that like the 2006 storyline "Civil War", the storyline of "Fear Itself" was inspired by the real world, in particular the perceived malaise and fear evoked by late 2000s events such as terror alerts, oil spills, the Great Recession and partisan politics. Explains Quesada:
"The climate in the world today was certainly the inspiration for this as we started to think about the bigger stories for the Marvel Universe," Marvel editor in chief Joe Quesada said at a press conference at Midtown Comics in Manhattan. "You will absolutely see the real world inject itself into this story because it's undeniable that there's a certain something in the air right now…we tend to tap into that whether consciously or unconsciously and it effects [sic] all our stories."
The storyline's title is a reference to a famous quote by Franklin D. Roosevelt: "So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself—nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance", as indicated by the use of a portion that quote as part of the soundtrack of the trailer presented during the Midtown press conference. The story's antagonist is the Serpent, an Asgardian being who sows doubt and fear among the superheroes of the Marvel Comics Universe, as illustrated by early promotional images for the event, which depict Spider-Man, Hulk, Captain America, Cyclops, Thor, and Iron Man coming face to face with their worst nightmares. During this conflict, which is referred to among the characters as the Serpent's War, the Serpent is revealed to be Cul, Odin's brother, who assumed the throne of Asgard following the death of their father. Born at the dawn of time, Cul was subsequently banished and imprisoned by Odin following Cul's corrupt rule, and a prophecy by Yggdrasil that cost Odin his right eye, and which revealed that Cul's madness could only be cured by the death of Odin's son.
Brevoort explained that all major characters are featured in the storyline, which involve a number of unconventional alliances, with even Marvel's version of Dracula participating in the event. Another god of fear, the adolescent Phobos, who is a member of the Secret Warriors, also appears in the series. Brevoort further explained that subtle hints of the storyline were planted well in advance, between approximately 15 months and two years prior to the miniseries, some of which may only be perceptible in hindsight. Brevoort and Alonso explained that although the story also ties into all of the company's other high-profile titles, and presents stakes as high as an "extinction-level event", the story could be understood by those who choose to read only the core Fear Itself miniseries. The related titles include the X-Men family of books, with the exception of X-Factor.
The Fear Itself prologue book, which was published in March 2011, features Captain America and Namor, and is produced by writer Ed Brubaker and artist Scot Eaton. The main Fear Itself miniseries, which debuted the following month, is written by Matt Fraction, and features illustrated interiors by Stuart Immonen and Wade von Grawbadger and covers by Steve McNiven. Fear Itself #1 is priced at $3.99 USD, and was projected to be about 45 pages long, according to Brevoort. (The first issue, when published, was 56 pages long.) Brevoort also indicated that the final issue would also be oversized, as is typical with such event miniseries. (The final issue was 64 pages long, 16 of which were devoted to epilogues that set up subsequent spinoff books.)
To promote Fear Itself: Fearsome Four #1, one of the tie-in books, writer
Brandon Montclare and artists Michael Kaluta and Ryan Bodenheim appeared at Midtown Comics Downtown on June 8, 2011, where they signed copies of the book. Writers Greg Pak, Fred Van Lente and editor Mark Paniccia later held a signing at the same store on June 18 for Alpha Flight #1, which is also part of the storyline.
A 12-issue, biweekly spinoff miniseries of "Fear Itself" titled The Fearless, debuted October 19, 2011. The series, which depicts Captain America, the Avengers and others dealing with the aftermath of the events of "Fear Itself", is written by Fraction, Cullen Bunn and Chris Yost, and is illustrated by Mark Bagley and Paul Pelletier. Other aftereffects of the crossover are explored in a series of one-shots under the title Shattered Heroes, in a manner similar to how the 2010 "Heroic Age" storyline served as a follow-up to the 2008-2009 "Dark Reign" storyline. Shattered Heroes is part of "Battle Scars", a rebranding of the Marvel Universe books most affected by "Fear Itself".