Wolverine is a superhero who appears in American comic books published by Marvel Comics. The character first appeared in the comic book The Incredible Hulk #180 (1974) and is best known as a member of the superhero team the X-Men. Wolverine is the alias of James Howlett (also known as Logan), a mutant born in Canada in the late 19th century. He possesses a range of superpowers including highly advanced self-healing abilities, a significantly prolonged lifespan, animal-keen senses, and retractable claws. His skeleton is reinforced with the unbreakable fictional metal adamantium, which he acquired after becoming an unwilling test subject in the Weapon X super soldier program. Wolverine is commonly depicted as a gruff loner susceptible to animalistic "berserker rages" who struggles to reconcile his humanity with his wild nature.

The character was co-created by writer Len Wein and Marvel art director John Romita Sr., with his first published appearance written by Wein and drawn by artist Herb Trimpe. After joining the X-Men in 1975, the character was significantly developed by writer Chris Claremont, artist Dave Cockrum, and artist-writer John Byrne. He gained greater prominence as a standalone character when artist Frank Miller collaborated with Claremont on a four-isue eponymous limited series in 1982, which debuted the character's catchphrase: "I'm the best there is at what I do, but what I do best isn't very nice."

Wolverine quickly emerged as the breakout character of the X-Men, and is among the most popular Marvel Comics characters. His willingness to use deadly force and his brooding loner nature became defining attributes of the many comic book antiheroes that emerged in the aftermath of the Vietnam War. In addition to his comic appearances, Wolverine has been depicted in a wide range of adapted and spin-off media, including television, video games, and film. Actor Hugh Jackman has portrayed the character in eleven films, beginning with X-Men (2000) and most recently in Deadpool & Wolverine (2024).

Marvel Comics editor-in-chief Roy Thomas wanted to create a Canadian superhero and decided that wolverines were a typical Canadian animal that could inspire such a hero. He asked artist John Romita Sr. and writer Len Wein to devise a character of Canadian origin named Wolverine. Romita designed Wolverine's costume. Wolverine first appeared in the final "teaser" panel of The Incredible Hulk #180 (cover-dated October 1974), written by Wein and penciled by Herb Trimpe. The character then appeared in a number of advertisements in various Marvel Comics publications before making his first major appearance in The Incredible Hulk #181 (November 1974), again by the Wein–Trimpe team. In 2009, Trimpe said he "distinctly remembers" Romita's sketch and that, according to him, Romita and Wein "sewed the monster together [while he] shocked it to life". According to him, Wolverine was initially conceived as a minor character and there were no plans for his continuing popularity. Though sometimes credited as co-creator, Trimpe denied having had any role in Wolverine's creation. The character's introduction was ambiguous, revealing little beyond his being a superhuman agent of the Canadian government. He appears briefly in the following issue's conclusion to the story.

Wolverine's next appearance was in Giant-Size X-Men (May 1975), written by Wein and penciled by Dave Cockrum, in which he is recruited for a new team of X-Men to rescue the original group. Gil Kane illustrated the cover artwork but drew Wolverine's mask with larger headpieces. Cockrum incorporated Kane's alteration into his artwork for the story.

At the time of his initial appearances, basic ideas about Wolverine's abilities and origins remained in development. While some sources indicate that Wein originally intended for Logan to be a mutated wolverine cub, evolved to humanoid form by the High Evolutionary, an established geneticist in the Marvel Universe, Wein has denied this, and suggested that this may have been Cockrum's idea. In an article about the evolution of Wolverine included in Incredible Hulk and Wolverine (1986), a reprint of The Incredible Hulk #180–181, Cockrum confirmed that he considered having the High Evolutionary play a vital role in making Wolverine a human.

In Wein's original conception, Wolverine was a young adult, and his claws were retractable and part of his gloves, with both made of adamantium. Romita said that he always envisioned the claws as retractable, explaining: "When I make a design, I want it to be practical and functional. I thought, 'If a man has claws like that, how does he scratch his nose or tie his shoelaces?'" Wein recollects that Cockrum first suggested that the claws were installed in Wolverine's forearms.

Following Giant-Size X-Men, the X-Men comic was revived with issue #94 (August 1975), drawn by Cockrum and written by Chris Claremont. Wolverine is initially overshadowed by the other characters, although he creates tension in the team as he is attracted to Cyclops' girlfriend, Jean Grey. As the series progressed, Claremont considered dropping Wolverine from the comic; Cockrum's successor, artist John Byrne, championed the character, later explaining that as a Canadian himself he did not want to see the only Canadian character dropped. Byrne modeled his rendition of Wolverine on actor Paul D'Amato, who played Dr. Hook in the sports film Slap Shot (1977). Cockrum introduced another costume for Wolverine in the final issue of his run, but it was dropped at the start of Byrne's run because he found it difficult to draw.