"Extraordinary Girl" is the ninth track of the Green Day album American Idiot. It is three minutes and thirty-three seconds in duration.

The song is about the character in Green Day's rock opera album American Idiot. It is a continuation of the description Jimmy's feelings for 'Whatsername'. The unusual percussion instruments in the song's intro (bongo drums in particular), combined with the electric sitar that joins it eight measures later, give the song a Middle Eastern feel until a standard drum kit and electric guitar take over where the sitar and bongos leave off. This introductory segment is evocative of The Beatles' music circa 1966, when John Lennon and Paul McCartney introduced increasingly exotic instruments into the repertoire of rock.

Extraordinary Girl is in the key of A; the aforementioned intro is taken at 112 bpm which segues into the song proper at 142 bpm.

Saint Jimmy meets 'Whatsername' in the song She's a Rebel and they begin dating. As Jimmy falls thoroughly in love with her, he is torn between living the way she does and the way Jesus of Suburbia, his alter-ego wants him to. As later seen in "Letterbomb," Whatsername wants him to fight for the city, whereas Saint Jimmy doesn't care. In the CD case lyric book, part of the song is written in Whatsername's handwriting, mainly the part of the song that describes "him".

The song could also imply that Whatsername only "got with" Jimmy because she was desperate to be loved/for someone to love, shown in the line "she sees a mirror of herself/ an image she wants to sell/ to anyone willing to buy".