Alan Greenspan is an American economist who served as Chairman of the Federal Reserve of the United States from 1987 to 2006. He currently works as a private adviser and provides consulting for firms through his company, Greenspan Associates LLC. First appointed Federal Reserve chairman by President Ronald Reagan in August 1987, he was reappointed at successive four-year intervals until retiring on January 31, 2006, after the second-longest tenure in the position.

Greenspan came to the Federal Reserve Board from a consulting career. Although he was subdued in his public appearances, favorable media coverage raised his profile to a point that several observers likened him to a "rock star". Democratic leaders of Congress criticized him for politicizing his office because of his support for Social Security privatization and tax cuts, which they felt would increase the deficit. The easy-money policies of the Fed during Greenspan's tenure have been suggested by some to be a leading cause of the subprime mortgage crisis, which occurred within months of his departure from the Fed, and have, said the Wall Street Journal, "tarnished his reputation" despite his warnings of "irrational exuberance". Yale economist Robert Shiller argues that "once stocks fell, real estate became the primary outlet for the speculative frenzy that the stock market had unleashed".