Alexisonfire is a Canadian post-hardcore band formed in St. Catharines, Ontario in 2001. The band's members are George Pettit (vocals), Dallas Green, Wade MacNeil, Chris Steele (bass) and Jordan Hastings. The band has won numerous awards, and in Canada their albums have all been certified either gold or platinum.

Post-hardcore is a punk rock music genre that maintains the aggression and intensity of hardcore punk but emphasizes a greater degree of creative expression. Like the term "post-punk", the term "post-hardcore" has been applied to a broad constellation of groups. Initially taking inspiration from post-punk and noise rock, post-hardcore began in the 1980s with bands like Hüsker Dü and Minutemen. The genre expanded in the 1980s and 1990s with releases by bands from cities that had established hardcore scenes, such as Fugazi from Washington, D.C. as well as groups such as Big Black, Jawbox, Quicksand, and Shellac that stuck closer to post-hardcore's noise rock roots. Dischord Records became a major nexus of post-hardcore during this period.