"I'm Not the Only One" is a song recorded by English singer and songwriter Sam Smith from his debut studio album, In the Lonely Hour (2014). It was written by Smith with Jimmy Napes, who also produced the song along with Steve Fitzmaurice. Capitol Recordsreleased it to digital download on 31 August 2014 as the album's third single in the United Kingdom and on 24 September 2014 as the album's second single in the United States; an alternative version with American rapper A$AP Rocky was also released.
A piano soul ballad, anchored by orchestral strings and a gospel structure, "I'm Not the Only One" deals with themes of infidelity in a relationship and was inspired by a marriage of someone Smith and Napes knew. It received a positive response from critics, who praised his emotional vocals and its instrumentation. Commercially, the song was another success for Smith, becoming a top-three hit in the United Kingdom, a top-five hit in the United States, and a top-ten hit in over ten countries. A music video featuring actorsDianna Agron and Chris Messina was released on 1 August 2014 and it features similar content than the song's lyrics.