The historical figure known for their role in the founding of the United Nations is Franklin D. Roosevelt. As the President of the United States during World War II, Roosevelt was a driving force behind the establishment of the UN, advocating for a cooperative international organization to prevent future conflicts. His vision for a post-war world order emphasized human rights, economic cooperation, and peacekeeping. Roosevelt's leadership at the San Francisco Conference in 1945, where the UN Charter was drafted and adopted, cemented his legacy as a key architect of this vital institution in global governance.