Dolly Parton, Patsy Cline, Hank Williams, Sr., Merle Haggard, Johnny Cash, John Prine, Hank Snow, Bill Monroe, Buck Owens, Carl Perkins, Roger Miller, Willie Nelson, Gram Parsons, Linda Ronstadt, Dwight Yoakam
& I suppose Porter Wagoner too, since I mentioned Dolly first.
http://en.wikipedia.org/wiki/List_of...formers_by_era