"Bad Guy" (stylized in all lowercase) is a song recorded by American singer Billie Eilish. It was released by Darkroom and Interscope Records as the fifth single from Eilish's debut studio album When We All Fall Asleep, Where Do We Go? 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 electropop, dance-pop, 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, and further touches on themes about misandry and sarcasm.