Relient K is an American rock band formed in Canton, Ohio in 1998 by Matthew Thiessen on guitar and piano, Brian Pittman on bass, and Matt Hoopes on guitar between the band's junior year in high school and their time at Malone College in Canton, Ohio. The band is named after guitarist Matt Hoopes' Plymouth Reliant K car, with the spelling intentionally altered to avoid trademark infringement over the Reliant name.

The group is associated with the Contemporary Christian Music culture, most notably the Christian rock and Christian punk scene. Despite being a Christian band the group has performed alongside secular artists, and has had critical success with mainstream pop punk. The band's sound incorporates piano rock and acoustic elements; and the lyrical content often refers to God, Jesus, and the terms "you" and "Him" are used in reference to The Divine. Since its formation, Relient K has released a discography consisting of five studio albums, seven EPs, two Christmas albums, and one collection of rarities. The band has received numerous awards including a Grammy Award nomination in 2003 for Best Rock Gospel Album and two Dove Awards.

Relient K is best known commercially for their two studio albums which peaked in the top 15 of the US Billboard 200 chart. After signing with Capitol Records, they broke into the mainstream in 2004 with the release of Mmhmm, which debuted at #15 on the Billboard 200. In 2007, their fifth album brought the most success for Relient K, Five Score and Seven Years Ago debuted at #6 on the US Billboard 200 and sold 60,000 records in its debut week. The band has sold over 2 million records, with three albums being given Gold certification by the RIAA. The band is also highly successful throughout the Christian Albums and Contemporary Christian Music charts.