Ornette Denardo Coleman. He became the drummer in his dad's trio at the age of 10 - not because he was a prodigy, but because he had nothing to unlearn, perfect for the New Frontier of free jazz. Appearances on LPs like The Empty Foxhole and Ornette at 12 were controversial then and now (it made for a nasty rec.music.bluenote thread), but he acquitted himself well. As a grown-up, he has drummed in Ornette's Prime Time electric group and has handled production chores.