Zao (IPA: /ˈzeɪoʊ/) is a band from Greensburg, Pennsylvania and one of the founding metalcore groups. 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. Singer Daniel Weyandt and guitarists Scott Mellinger & Russ Cogdell are seen by most fans as the "core" of Zao.

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 members identified themselves as Christians, Zao no longer considered itself a Christian band but rather a group of open-minded artists. However in an interview posted on their myspace, their manager pointed out that due to another line up change they were all Christian. Guitarist Scott Mellinger described the bands view on religion by saying this "We're not selling Christ. We're just following Him!." Lyrics in future productions may or may not include Christian messages, but they have also stated they would love to play at Cornerstone again, which is an exclusively Christian music festival.

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.