Celtic Frost was a Swiss extreme metal band from Zürich. They were formed in 1981 by vocalist and guitarist Tom Warrior and bassist and vocalist Martin Eric Ain. The band was one of the first to combine elements of extreme metal and avant-garde music. They released several albums throughout the 1980s, and were influential in the development of the subgenres of black metal and death metal. Their style was characterized by a dark, heavy sound, complex song structures, and occult and horror-inspired lyrics.