A significant figure in the establishment of the United Nations is Franklin D. Roosevelt. As the President of the United States during World War II, Roosevelt played a pivotal role in advocating for the creation of an international organization aimed at preventing future conflicts. He was instrumental in the Atlantic Charter discussions and worked closely with other Allied leaders to establish the UN at the end of the war. His vision of collective security and international cooperation laid the groundwork for the UN's principles, promoting peace, development, and human rights on a global scale.