Killswitch Engage is an American metalcore band from Westfield, Massachusetts, formed in 1999. The band's current lineup consists of vocalist Jesse Leach, guitarists Joel Stroetzel and Adam Dutkiewicz, bassist Mike D'Antonio, and drummer Justin Foley. Howard Jones was the band's lead vocalist from 2002 to 2012.

Leach was the band's founding vocalist but left after two albums. He was replaced by Jones, and Killswitch Engage rose to fame with its 2004 release The End of Heartache, which peaked at number 21 on the Billboard 200 and was certified gold by the RIAA for over 500,000 shipments in the United States. The title track was nominated for a Grammy Award in 2005 for Best Metal Performance. The band's fourth album, As Daylight Dies, was certified platinum in the US and spawned the platinum-selling single "My Curse".

Jones departed in 2012 and Leach returned to his founding position. Disarm the Descent (2013), the band's first album since Leach's return, went top 10 in the US and featured the Grammy-nominated single "In Due Time". The band's upcoming ninth album, This Consequence, is set to be released on February 21, 2025.

Killswitch Engage has sold over four million records in the U.S. and has been considered notable within the New Wave of American Heavy Metal, and has also been considered one of the earliest leading forces of the metalcore genre.