Who started it: Kanye West
Circa: Late 2010 

An early adopter of Riccardo Tisci's Givenchy menswear, Kanye was always about more than the animal-print graphic tees. Before he achieved style notoriety with his leather skirt, he wasn't afraid to wear leather pants. Less than a couple of years later, the "street goth" movement is in full effect, and brands like En Noir are making high-end leather versions of sweatpants and basketball shorts.