"Helena" (sometimes titled "Helena (So Long & Goodnight)" on digital retailers such as iTunes) is a song by American rock band My Chemical Romance, and is the third single from their second studio album, Three Cheers for Sweet Revenge. The lyrics describe lead singer Gerard Way and bassist Mikey Way's feelings for their late grandmother, Elena Lee Rush (whom her friends referred to as "Helen", and because of this, Gerard always thought to combine her first name with this alias, forming the name, "Helena").

NME declared that the song was one of the "20 Greatest Goth Tracks" and that it was "a pivotal moment in cross-fertilising goth with emo" and that "MCR spawned a hybrid that ensured black clothes and eyeliner became, once again, teenage rebellion's default setting".