Supercollider / The Butcher is a single by Radiohead, released as a double A-side single on 12-inch vinyl in the UK, Europe, and Japan on 16 April 2011 for Record Store Day. The single 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 had ordered the album.
The Butcher was recorded and mixed during the King of Limbs sessions, but excluded from the album as it did not fit with the other tracks. Singer Thom Yorke first performed Supercollider solo 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, after the album's release.