Ayn Rand
Ayn Rand was an incredibly important part of both Greenspan's personal and professional life. They met when Greenspan was a young economic forecaster working at New York University. Greenspan would attend many of Ayn Rand's secret meetings at her New York apartment in order to read draphs of her novel Atlas Shrugged. Greenspan himself was primarily attracted to Ayn Rand's defense of capitalism through her moral teachings. He developed a fond appreciation of her teachings, and many of her "objectivist" idealogies were seen later in Greenspan's management at the Federal Reserve. Ayn Rand's picture of capitalism as the ultimate force of good was a very powerful message for Greenspan.
Arthur Burns
Arthur F. Burns was the Chairmen of the Federal Reserve from 1970-1978. After serving his tenure, he went on to teach at Columbia University, where he met a young student named Alan Greenspan. While Greenspan did not stay long, Burns made a lasting impression on him. Being a strictly "stop-go" monetary theorist, that is he adhered strictly to monetary rules at all costs, deeply influenced some of Greenspan's decisions later in life. Greenspan, like Burns, was set deeply in his ways and had a hard time listening to advice. Both men played key roles in their respective administrations and both men created some of the largest credit and inflation issues seen in American history.