SS501 is a quintessential K-pop boy band with a novel name: the “SS” stands for “superstar singer,” and “501” means “five members united forever as one.” Their songs are equally unique, with mid-song key changes (see: the escalating chorus of “U R Man”) and surprising sounds (like the mix of synth percussion, distorted guitars, and breaking glass on “Déjà Vu”) mixed into the production. Though on hiatus since 2010, the members' successful solo careers ensure that SS501's legacy lives on.