Defeater is an American melodic hardcore band from Massachusetts, formed in 2008.

The band lineup consists of Derek Archambault (vocals), Jake Woodruff (guitar), Joe Longobardi (drums) and Mike Poulin (bass).

Defeater has toured with the likes of La Dispute, Carpathian, Comeback Kid, Bane, Energy.

All of their music serves as narration over one overarching story, telling of the struggles of a working class New Jersey family in the Post-World War II Era.

Vocalist Derek Archambault stated in a 2009 interview that all of Defeater's work would take place within this story.