Zao is a metalcore band from Greensburg, Pennsylvania, which is widely considered to have pioneered the boundaries of Christian metal music [citation needed]. Founded in 1993 in Parkersburg, West Virginia, Zao has hosted several musicians and endured numerous roster changes to the point where no original members remain.

Christianity has been a key influence in the band's work; because the founding members claimed to have a strong relationship with God, they were considered a devoted Christian band, which changed as time passed. Jesse Smith slowly changed his vision for the band, preferring it to be not a 100% Christian band. As Dan Weyandt entered the band, the lyrics changed drastically, mostly leaving a message that he is alive because of God, not with the intention of spreading the religion, but to let know how it helped him in his personal struggles. Because only half the band's present members identify themselves as Christians, Zao no longer considers itself a Christian band but rather a group of open-minded artists.

To date, Zao has completed nine full-length albums, three EPs, a two-disc DVD documentary and multiple concert tours, garnering a limited but global fanbase and setting genre standards in the process.