Hate Today’s Biggest American Pop Songs? Blame Canada.

When Henry Walter drives down Sunset Boulevard and one of the songs he’s co-written plays on the radio—maybe Katy Perry’s Roar, or Rihanna’s Where Have You Been, or Ke$ha’s Die Young, or Miley Cyrus’sWrecking Ball—he gets reflective. “Every day, I’m thankful,” he says. “I pinch myself; this is crazy.” But sometimes, the 27-year-old Ottawa native, who writes and produces music as Cirkut, wonders, “Am I ever going to have a hit again? How long can I keep this going?’”Walter has been working in L.A. for the past three years—an eternity in the pop world. He’s spent most of it at the right hand of hitmaking producer Lukasz “Dr. Luke” Gottwald, whose chart achievements, starting with Kelly Clarkson’s Since U Been Gone in 2004, are legendary. In that time, Walter has evolved from an assistant (or what he calls “a nerdy, laptop-and-make-beats kind of guy,” creating rhythms and fleshing out Luke’s ideas) to a collaborator who produces vocals and works directly with the stars. “It’s easy enough to get in the room with some of these people once,” says his entertainment lawyer, Toronto’s Chris Taylor (who also works with Drake and Nelly Furtado), “but to be continually invited back, you need the right combination of work ethic and amenability.”