Defeater is a melodic hardcore band from Massachusetts, USA. To date they have released three full-length albums, two EPs and a single. The band lineup consists of Derek Archambault (vocals), Jay Maas (guitar), Jake Woodruff (guitar), Joe Longobardi (drums) and Mike Poulin (bass). All of the band's works have been released via Bridge 9 Records, aside from the album Travels, which was initially released via Topshelf Records, but was later reissued on Bridge 9 Records. Their latest studio album, Letters Home, was released on July 16th, 2013 and debuted at number 72 on Billboard Top 200 chart, number 1 on the vinyl chart and number 13 on the Current Alternative Album chart.

They have toured with the likes of La Dispute, Carpathian, Comeback Kid, Bane and Miles Away. They supported August Burns Red in 2013.