Isis was an American post-metal, sludge metal, and avant-garde metal band formed in Boston, Massachusetts, in 1997 by guitarist and vocalist Aaron Turner. The group initially included Jeff Caxide on bass, Chris Mereschuk on electronics and vocals, and Aaron Harris on drums. Following lineup changes that included the addition of Bryant Clifford Meyer and Michael Gallagher, the band released their debut studio album, Celestial (2000), gaining underground attention. In 2002, they signed with Ipecac Recordings and released Oceanic, which marked a shift towards post-rock and ambient music. The album received critical acclaim and was named album of the year by the music magazines Rock Sound and Terrorizer. Subsequent releases include Panopticon (2004), which featured guest bassist Justin Chancellor of Tool and reached number 47 on the Billboard independent albums chart, In the Absence of Truth (2006), which reached number 6 on the Billboard charts, and Wavering Radiant (2009). The band announced their disbandment on May 18, 2010, and their final performance took place in Montreal on June 23, 2010.