Final answer:
Franklin D. Roosevelt was the notable person missing from the Potsdam Conference, as he had passed away before the conference took place.
Step-by-step explanation:
One notable person missing from the Potsdam Conference was Franklin D. Roosevelt, the former President of the United States. He had passed away in April 1945, prior to the conference. During the Potsdam Conference, his successor, Harry S. Truman, represented the United States. Discussions at this conference revolved around post-World War II arrangements and the reconstruction of Europe. The leaders present, including Truman, new British Prime Minister Clement Attlee, and Soviet Premier Joseph Stalin, decided to divide Germany and Berlin into American, British, French, and Soviet sectors.