Alan Greenspan, former Fed chair for nearly two decades, guided US monetary policy through an era of low inflation and growth with "easy money." His tenure featured the "Greenspan put" and "Greenspan effect," making him immensely powerful. Credited for identifying 1990s productivity gains and "irrational exuberance," his low rates were later linked to the subprime crisis and a housing bubble, which he ambiguously acknowledged. Despite criticism, Greenspan's legacy of easy monetary policy and his views significantly influence central bankers and global policy today, demonstrating his enormous, lasting impact.