The Sanctus is a hymn in Christian liturgy. It may also be called the epinikios hymnos when referring to the Greek rendition and parts of it are sometimes called "Benedictus". Tersanctus is another, rarer name for the Sanctus. The same name is sometimes used for the Trisagion.

The Trisagion, sometimes called by its opening line Agios O Theos, is a standard hymn of the Divine Liturgy in most of the Eastern Orthodox, Western Orthodox, Oriental Orthodox, and Eastern Catholic churches.