Iron Maiden + Alice Cooper

In any discussion of rock acts that have improved with age, English heavy-metal institution Iron Maiden has to come in somewhere near the top: Even if Bruce Dickinson can't hit every screeching high note of his prime, he deploys his resources for maximum impact, something that could be said equally for his restless bandmates. Alice Cooper, too, has never stopped taking risks, as his cover of Lady Gaga's "Born This Way" at this year's Bonnaroo Festival showed; listen closely to the lyrics, though, and you realize they suit the godfather of shock to a tee.