Kendall, Gigi, Adriana, Lily, Bella, Alessandra and co. are off and strutting for the Victoria's Secret Fashion Show ... and it's got an awesomely dark and sexy twist this year.

Most of the models are sporting lingerie that seems way more S&M inspired for the Dark Angel theme -- and ain't a damn thing wrong with this dark side.

Lady GagaBruno Mars and The Weeknd are performing -- and he got a big smile out of his supposed ex, Bella, during dress rehearsal. Who says breaking up is hard to do?