How about great underappreciated male singers of the 20th century?
General Johnson provided the unforgettable stuttered vocal on "Give Me Just A Little More Time" By Chairman of The Board. He also sang lead for The Showmen on "It Will Stand", "39-21-41 Fit", and "This Misery", among others. He also wrote and sang the original version of "Patches" one of the great sappy guilty pleasures of the '70's.
Not a great voice, but from late '50's doo wop, through '70's Motown-esque soul-pop, into straight schlock pop and even now, this guy made good (and often not so good) songs truly memorable by virtue of his interpretation.