Rudolph William Louis Giuliani, known as Rudy Giuliani, is an American attorney, cybersecurity advisor, and former politician who served as the 107th Mayor of New York City from 1994 to 2001. He previously served as U.S. Attorney and federal prosecutor, was a 2008 Republican presidential candidate, and later became U.S. Ambassador to the United Nations. A prominent Republican lawyer, he acted as a personal attorney, key advisor, and political operative to Donald Trump. Giuliani is known for his law-and-order stance, tough positions on national security and foreign policy, pro-Israel advocacy, his role in the 9/11 response and post-9/11 leadership, and his later Trump affiliations, including as a key figure in 2020 election challenges who promoted conspiracy theories about voter fraud.