John O'Sullivan is an Irish-American journalist and political commentator known for his work in conservative media. He gained prominence as the founding editor of the magazine National Review and has contributed to various publications, including The Wall Street Journal and The New York Times. O'Sullivan is recognized for his insights on political issues and his advocacy for free-market principles. In addition to his journalism, O'Sullivan has been involved in political strategy and has served as an advisor to several conservative politicians. He is also known for coining the term "Manifest Destiny," which describes the 19th-century belief that the expansion of the United States across the American continents was both justified and inevitable.