Eminem landed on the late ‘90s rap scene with a cheeky, uncompromising attitude that was as willfully immature as it was culturally incisive. His persona is on full display in videos like “The Real Slim Shady,” which has him commenting on human sexuality while running around in superhero outfits, and “Without Me,” where he teams up with Dr. Dre for a comic-book send-up of censorship laws.