Robert Plant Elvis Presley Frank Sinatra Bob Dylan (yes really) Janis Joplin Ella Fitzgerald Pavarotti
I'll 2nd, Ella Fitzgerald. Billy Holiday. Amy Winehouse. Jackie Wilson. Alison Moyet. Andrea Bocelli. Once you start there's no end.
Hannah Craddick (née Stobart) who recorded 2 acoustic albums with Steve Rothery (Marillion) under the band name 'The Wishing Tree'
Jeff Buckley, Marvin Gaye, Cat Power, Julian Casablancas, Sam Cooke, Johnny Cash, Johanna and Klara Söderberg (as a duo)....
Freddie Mercury and Whitney Houston. Freddie was so good and had such a wide range there have been scientific studies of how he did it. He could sing from bass to soprano.
He had 4 more top teeth than the average adult male and was often advised to have them fixed (appearance reasons) he always refused for fear of it forever affecting his singing voice.
I attended an audience with Brian Blesded at Scarborough Spa about 3 or 4 years ago. He talks about Stars in their eyes where he once performed as Pavarotti. At the end of the show he sang Nessun Dorma and brought the house down and the audience to a standing ovation.