"Alone" is a song by American singer Halsey from her second studio album Hopeless Fountain Kingdom (2017). A remixed version of the song featuring American rapper Big Sean and British rapper Stefflon Don was released on March 15, 2018 through Astralwerks as the third and final single from the album.
"Alone" contains a sample from "Nothing Can Stop Me", written by Tony Hester and recorded by Marilyn McCoo and Billy Davis Jr.. "Alone" follows "kinda like this Gatsby vibe," as stated by Halsey. It's about a social butterfly at the house party (which is a parallel to the masquerade ball in Romeo and Juilet) referenced in "Heaven In Hiding" and "Strangers". It is the second character's perspective of this party, with "Heaven In Hiding" acting as the first character's perspective.