"Bad Guy" is a song recorded by American singer-songwriter Billie Eilish. Darkroom and Interscope Records released it as the fifth single from her debut studio album When We All Fall Asleep, Where Do We Go? on March 29, 2019. Eilish and her brother Finneas O'Connell co-wrote "Bad Guy", with the latter producing it and the former providing additional production. The song was described as pop-trap and nu-goth pop in press reviews, for which synth bass, a kick drum, finger snaps and 808 bass provide minimalist instrumentation. During the song's lyrics, Eilish taunts her lover for being a bad guy although suggesting that she is more resilient than he is. The song is also about misandry and sarcasm.