Celtic Frost /ˈkɛltɪk frɒst/ was a Swiss metal band from Zürich. They are known for their heavy influence on the extreme metal genres. The group was first active from 1984 to 1993, and re-formed in 2001. Following Tom Gabriel Fischer's departure in 2008, Celtic Frost disbanded. The band was inspired by heavy metal groups such as Black Sabbath, Judas Priest and Venom, but also by gothic rock acts like Bauhaus, Siouxsie and the Banshees and Christian Death, and by the hardcore punk group Discharge.

Their exact genre has been a topic of debate. Their earlier music was sometimes classified as thrash metal, black metal and even death metal and their later work as doom metal and gothic metal. The level of experimentation on albums such as Into the Pandemonium led certain journalists to describe the band's direction as avant-garde metal.