Okay, first of all give yourself a huge slap in the face for even asking that stupid quesion. You should know who he is. He has probably inlfulenced your life in ways you wouldn't even know about.

HE IS THE MAN.

According to Wikipedia (which Alan Greenspan wrote singlehandedly... without any hands)

Alan Greenspan (born March 6, 1926) is an American economist and was Chairman of the Board of Governors of the Federal Reserve of the United States from 1987 to 2006. Following his retirement as Fed chairman, he accepted an honorary (unpaid) position at HM Treasury in the United Kingdom.

First appointed Fed chairman by President Ronald Reagan in August 1987, he was reappointed at successive four-year intervals until retiring on January 31, 2006, at which time he relinquished the chairmanship to Ben Bernanke. Greenspan was lauded for his handling of the Black Monday stock market crash that occurred very shortly after he first became chairman, as well as for his stewardship of the Internet-driven, "dot-com" economic boom of the 1990s. However, this expansion culminated in a stock market bubble burst in March 2000 followed by a recession in 2001–2002.

From 2001 until his retirement, he was increasingly criticized for some statements seen as overstepping the Fed's traditional purview of monetary policy, and others viewed as overly supportive of the policies of President George W. Bush, as well as for policies seen as leading to a housing bubble. Greenspan was nonetheless still generally considered during that time to be the leading authority on American domestic economic and monetary policy, and his active influence continues to this day.