Best Male Singers of the 20th Century

There is an interesting current discussion about the best female vocalists on CD. I have my own ideas about the best male singers (any category) of the 20th Century, but would like to hear other opinions.
I don't know about the best, as this is a complicated question, but one name that comes to mind rather quickly is George Michael. Check out his cd "songs from the last century."
John McCormack up to 1924. You have to be willing to listen to transcriptions of old acoustic recordings. These take some getting used to but can be remarkably rewarding.