'Supercollider/The Butcher' is a 2011 single released on 12-inch vinyl in the UK, Europe and Japan on 16 April 2011 for Record Store Day. Released on the same format in the United States and Canada on 14 June 2011.
'Supercollider' was debuted on 6 June 2008 at Malahide Castle, Dublin. It was subsequently played at various Radiohead and Thom Yorke/Atoms for Peace shows leading up to its official release.
Digital masters of the tracks were released in WAV and MP3 on 18 April 2011 through the The King of Limbs website to those who pre-ordered the album.
According to the band, 'Supercollider was recorded and mixed during The King of Limbs sessions', 'and finished off in March of this year'.
'Supercollider' is the longest original studio track released by Radiohead, beating Paranoid Android by 38 seconds.