Too many to list over the years, and some were "Discovered" at around the same time period but in different areas of the country, by different people. So it's never totally clear cut.
Like Kegsy says, it was only by handing the records to big Dj's to play that brought them to the fore. Some people may have had the same record for years before it broke on the scene.
Round these parts, Steven {Brad} Bradley was the man.