Pyro is the name of two characters appearing in American comic books published by Marvel Comics.

The first character known as Pyro is St. John Allerdyce, a recurring enemy of the X-Men and later an agent of the U.S. government. He was created by Chris Claremont and John Byrne and introduced in The Uncanny X-Men #141 (January 1981) as part of the Brotherhood of Mutants. Pyro has the mutant power to control fire, but not create it. Pyro and the Brotherhood of Mutants are the antagonists in the X-Men story Days of Future Past as they attempt to assassinate Senator Robert Kelly, which in an alternate timeline leads to a dystopic future where Mutants are hunted, killed or captured by the Sentinel robots. The assassination is thwarted, and at a later date the Brotherhood become agents of the US government in exchange for a full pardon, and the team becomes known as the Freedom Force.

The second character known as Pyro is Simon Lasker, an American teenage mutant with the ability to create and control fire. Lasker was created by Marc Guggenheim and Ardian Syaf and introduced in X-Men Gold (Vol. 2) #1 (April, 2017). He was initially hypnotized by Mesmero into joining his Brotherhood of Mutants, but later joined the X-Men.

An Americanized version of Pyro named John Allerdyce appeared in the X-Men film franchise produced by 20th Century Fox. He was portrayed by Alexander Burton in X-Men (2000), and was subsequently replaced by Aaron Stanford for its sequels X2 (2003) and X-Men: The Last Stand (2006), and the Marvel Cinematic Universe (MCU) film Deadpool & Wolverine (2024).

Created by writer Chris Claremont and artist/co-writer John Byrne, the St. John Allerdyce version of Pyro first appeared in The Uncanny X-Men #141 (January 1981).

As part of the Dawn of X initiative, Pyro subsequently starred in the Marauders series in October 2019 alongside Kitty Pryde, Iceman, Emma Frost, Storm, and Bishop.^{[citation needed]}

Simon Lasker as Pyro was introduced in the first three issues of X-Men Gold as a member of Mesmero's Brotherhood, leaving the team in issue 22 and joining the X-Men in the next issue. He stayed with the team until the titles end with issue 36, appearing in X-Men: The Wedding Special before this. He appeared in Marvel's Voices (Vol. 1) #1 before appearing dead in X-Force (vol. 6) #11 (August, 2020).

Born and raised in Sydney, Australia, St. John Allerdyce is a mutant who possesses the elemental power to control fire and flame, though not generate it. As such, he wields a flamethrower to provide heat for him to control. After years of working in Southeast Asia as a journalist and novelist, Pyro met the mutant Mystique, who later recruited him to the Brotherhood of Mutants as a professional criminal and subversive. With the Brotherhood of Mutants, he attempted to assassinate Senator Robert Kelly, and first battled the X-Men. With the Brotherhood, he later battled the Avengers, and then the X-Men again. Though he never served under the team's original leader, Magneto, Pyro did work with the Brotherhood under the command of several of Magneto's subordinates who alternately supervised the group.