Gann was a trader who was recognized for his market forecasts. He used price and time cycles to predict major highs and lows years in advance. He is reported to have made $50 million trading commodities and stocks during the 1920's. However the accuracy of his forecasts is still the subject of substantial debate and even Gann’s own son (who admittedly didn’t get on with his father) alleges that many of his claims were fraudulent. It’s also alleged that Gann lost the fortune he made and died a pauper in 1955.

For more information see the following links:
Wikipedia
http://en.wikipedia.org/wiki/William_Delbert_Gann
http://en.wikipedia.org/wiki/Gann_angles