4. Iron Maiden
There's almost no such thing as a casual Iron Maiden fan. People are either vaguely aware there's a metal band that sings that song "Run To The Hills," or they're wearing a vintage Fear Of The Dark Shirt at a Maiden show screaming at the top of their lungs for "Wrathchild." Not even Rush manages to fill arenas with nothing but super-hardcore fans. Frontman Bruce Dickinson joined the band in 1982 for their classic LP The Number of the Beast, and even though he took some time off in the Nineties to focus on his solo career, he's still leading the group. They just wrapped a world tour behind their 2010 LP The Final Frontier, but they should be back at it in another couple of years.