Vidal was born into a wealthy family as Eugene Vidal, Jr. His father, Eugene Vidal served under FDR as Director of the Bureau of Air Commerce. He also made a success of himself in aviation co-founding several airlines including Northeast Airlines which he started along with Amelia Earhart. It is believed that Vidal and Earhart were also romantic partners which the younger Vidal maintained was so. However, there is some dispute to these facts and his belief could have been the product of a wild imagination or wishful thinking. His maternal grandfather, Thomas Gore was a long serving Democratic Senator from Oklahoma. Vidal would later adopt his maternal grandfather's name.
Despite his prolific output, Vidal will probably be best remembered for his outlandish opinions and acerbic manner as demonstrated by this famous exchange between him and National Review founder William F. Buckley during the 1968 Democratic Convention in Chicago. While Buckley later regretted calling Vidal "a queer", Vidal apparently had no such regret in referring to Buckley as "a crypto-Nazi.'
One could make the case that Vidal significantly contributed to the decline of liberal thought. He engaged in conspiracy theories suggesting that both FDR knew about Pearl Harbor and that George W. Bush knew about the 9/11 attacks ahead of time. To give you an idea of Vidal's state of mind, he told Joy Behar that he thought Barack Obama was "too intelligent" to be President and that he wished he had murdered Bush much to the delight of Behar and her staff. Of course, if any writer were to have wished he had murdered Obama, Ms. Behar would be the first to issue a condemnation.
Vidal was also not fond of Jews. In 1986, he referred to American Jews as "Israeli fifth columnists" who "stay among us; in order to make propaganda and raise money for Israel."
I think Leon Wiseltelier, the longtime book editor for The New Republic, summed Vidal up best when he called him "Abu Vidal".