The Avengers is an American comic book series published by Marvel Comics that features the superhero team Avengers. The series first appeared in The Avengers no. 1 in September 1963, created by writer Stan Lee and artist Jack Kirby. It was developed as a team title that brought together established Marvel characters. It has since become one of the publisher’s longest-running and most prominent franchises.

The series has been relaunched and renumbered multiple times, reflecting changes in creative direction, continuity and publishing strategy. Its roster has included various characters, including Iron Man, Thor, the Hulk, Ant-Man, the Wasp, and Captain America, along with many others added over time. Stories usually focus on large-scale threats which individual heroes cannot face alone, a structure that helped define the team’s role in the larger Marvel Universe.

In 1960, DC Comics launched a comic book series featuring a team of superheroes called the Justice League. Impressed by that book's strong sales, Martin Goodman, the owner of Marvel Comics predecessor Timely Comics, asked Stan Lee to create a title featuring a similar team of superheroes for Marvel. Lee recounts in Origins of Marvel Comics:

Martin mentioned that he had noticed one of the titles published by National Comics seemed to be selling better than most. It was a book called The [sic] Justice League of America and it was composed of a team of superheroes. ... 'If the Justice League is selling,' spoke he, 'why don't we put out a comic book that features a team of superheroes?'

Much like the Justice League, the Avengers were an assemblage of pre-existing superhero characters created by Lee and Jack Kirby. Kirby did the artwork for the first eight issues only, in addition to doing the layouts for issues #14–16. This initial series, published bi-monthly through issue #6 (July 1964) and monthly thereafter, ran through issue #402 (Sept. 1996), with spinoffs including several annuals, miniseries and a giant-size quarterly sister series that ran briefly in the mid-1970s. Marvel filed for a trademark for "The Avengers" in 1967 and the United States Patent and Trademark Office issued the registration in 1970.

Between 1996 and 2004, Marvel relaunched the primary Avengers title three times. In 1996, the "Heroes Reborn" line, in which Marvel contracted outside companies to produce four titles, included a new volume of The Avengers. It took place in an alternate universe, with a revamped history unrelated to mainstream Marvel continuity. The Avengers vol. 2 was written by Rob Liefeld and penciled by Jim Valentino, and ran for 13 issues (Nov. 1996–Nov. 1997). The final issue, which featured a crossover with the other Heroes Reborn titles, returned the characters to the main Marvel Universe.

The Avengers vol. 3 relaunched and ran for 84 issues from February 1998 to August 2004. To coincide with what would have been the 500th issue of the original series, Marvel changed the numbering, and The Avengers #500-503 (Sept.– Dec. 2004), the one-shot Avengers Finale (Jan. 2005) became the "Avengers Disassembled" storyline and final issues. Avengers vol. 4 debuted in July 2010 and ran until January 2013. Vol. 5 was launched in February 2013. After Secret Wars, a new Avengers team debuted, dubbed the All-New, All-Different Avengers, starting with a Free Comic Book Day preview.

"And there came a day, a day unlike any other, when Earth's mightiest heroes and heroines found themselves united against a common threat. On that day, the Avengers were born—to fight the foes no single super hero could withstand! Through the years, their roster has prospered, changing many times, their glory has never been denied! Heed the call, then—for now, the Avengers Assemble!"