Tim Ferriss is an American author, entrepreneur, self-proclaimed "human guinea pig," and public speaker. He has written a number of self-help books on the "4-hour" theme, some of which have appeared on the New York Times, Wall Street Journal, and USA Today bestseller lists, starting with The 4-Hour Workweek. Ferriss is also an angel investor and an advisor to Facebook, Twitter, StumbleUpon, Evernote, and Uber, among other companies.