Most powerful non-metal vocalists

I think it's a given that heavy metal has some of the most dynamic singers in music. Even if you hate the genre, it's hard to deny the talent of guys like Bruce Dickinson, Ronnie James Dio, Rob Halford, etc.

But which non-metal vocalists have the pipes to go toe-to-toe with these metal gods?

I realize that a number of hard rock singers can easily be classified as 'metal vocalists' depending on how you interpret their band's sound (e.g. Deep Purple), but I also think it's typically easy to identify a singer as being predominantly rock or hard rock rather than metal.

These singers don't necessarily have the most well-trained chops, but their vocals can shatter glass and blow out your stereo speakers when turned to 11.

Here are some of my nominees just to get the ball rolling:

Ian Gillian
Brian Johnson
Roger Daltrey
David Coverdale (pre-Whitesnake)