John Denver was an American folk/country artist. He wrote this song, “Leaving, On a Jet Plane” as well as the very famous “Take Me Home, Country Roads”. (I guess he really liked putting commas in his song titles). Here’s a cool clip of him performing this song with Cass Elliot. The song was recorded by folk group Peter, Paul, and Mary in 1969 which helped popularize the song; you can read some of the history around that here. Slightly Stoopid also covered the song, which you can listen to here.