Gravitar were an American noise rock band formed in Detroit, Michigan, United States, formed in 1992 by Eric Cook, Harry Richardson and Geoff Walker. In 1995, Richardson parted ways with the band and was replaced by Michael J. Walker, Geoff's brother. Aside from heavy metal and psychedelic acts such as Black Sabbath and Blue Cheer, Gravitar's music is strongly influenced by experimental music, jazz, and is mostly improvisational.