I'm Not the Only One is a song by British singer-songwriter Sam Smith, released as the fourth single from his 2014 debut studio album In the Lonely Hour. It was co-written by Sam Smith and Jimmy Napes. The song peaked number three on the UK Singles Chart and number seven on the U.S. Billboard Hot 100. The music video was directed by Luke Monaghan. Starring in the video are Dianna Agron and Chris Messina.