"Reckoner" is a song by English alternative rock band Radiohead and is the seventh track on their 2007 album In Rainbows. The song was released as the fourth single from In Rainbows on 23 September 2008. It was released through the Radiohead Remix website in the form of 'stems', individual parts of the song (e.g. vocals, guitar, piano) for fans to remix, as with "Nude". The band had James Holden and Diplo create the first remixes of "Reckoner".
"Reckoner" on In Rainbows seems to bear little resemblance to the earlier incarnation of the song. When the album came out in October 2007, critics and listeners who had heard both versions remarked that the recorded version of "Reckoner" was calmer, taking the form of a ballad sung in falsetto, with dominant percussion and insistent, softer guitar riffs, and entirely different lyrics. The recording also features a string arrangement by guitarist Jonny Greenwood.
Late in 2007, members of Radiohead gave an interview to BBC Radio 1 in which they explained that the new "Reckoner" in fact came out of an attempt to record the earlier song with that title. Late in the sessions, Yorke and Greenwood tried adding a coda to the original version of the song, and eventually the band decided to abandon everything except the new coda, which became "Reckoner."