"Supercollider"/"The Butcher" is a single by the English alternative rock band Radiohead. It was released on 12-inch vinyl in the UK, Europe and Japan on 16 April 2011 for Record Store Day. It was released on the same format in the United States and Canada on 14 June 2011. Digital masters of the tracks were released in WAV and MP3 on 18 April 2011 through the King of Limbs website to those who ordered the album in any format before the single was released.
"The Butcher" was recorded and mixed during The King of Limbs sessions, but the band "couldn't make it work with the rest of the album". "Supercollider" was debuted as a solo Thom Yorke performance on 6 June 2008 at Malahide Castle, Dublin; studio work on the track was started during the King of Limbs sessions and finished in March 2011.