"Mr. Spaceman" is a song by the American rock band The Byrds and was the third track on their 1966 album Fifth Dimension. The song was initially written by band member Jim McGuinnas a "melodramatic screenplay" but it soon evolved into a whimsical meditation on the existence of extraterrestrial life. After its appearance on Fifth Dimension, "Mr. Spaceman" was released as the third single taken from that album in September 1966. The single reached #36 on the Billboard Hot 100 but failed to chart in the United Kingdom.