Not every famous musician started out confident in their musical style or genre. Whether it had to do with aggressive marketing schemes by record labels or inexperience and insecurity on the part of the artist, some popular names started out with a look and sound that didn't remotely resemble that of when they came into their own.
In one fairly terrifying example, classically trained pianist and composer Tori Amos started out as the front woman for a cheesy 80s synth pop band with the embarrassing name of "Y Kant Tori Read." Even if you don't like Tori Amos in her later years, I think many would agree that she's a least a step above drum machines, synth and mega-hair.
See videos and read about the earliest music of other acts including Genesis and The Beastie Boys here.