"Six Feet Under" is the debut single by American singer Billie Eilish. It was first released through SoundCloud on June 23, 2016. It was later re-released on November 17, 2016, by Darkroom and Interscope Records. Finneas O'Connell, Eilish's brother, solely wrote and produced the track. The track is described as a "somber" and "delicate" pop ballad. Commercially, it was certified platinum by Music Canada (MC).

Billie Eilish Pirate Baird O'Connell is an American singer and songwriter. She first gained public attention in 2015 with her debut single "Ocean Eyes", written and produced by her brother Finneas O'Connell, with whom she collaborates on music and live shows. In 2017, she released her debut extended play (EP), Don't Smile at Me. Commercially successful, it reached the top 15 of record charts in numerous countries, including the US, UK, Canada, and Australia.