In early March Kanye West and Jay-Z will release their long-awaited collaborative album Watch the Throne. The lead-off single “H.A.M” underwhelmed many fans, causing us to think back to the long history of all-star duets — some predictable, some completely unexpected. Sometimes they’re amazing (think Elton and Eminem). Other times they fall very flat (think Diddy with Jimmy Page). Here’s a look back at 19 more superstar duets from the past few decades.