Brien McMahon was an American politician who served as a United States Senator from Connecticut from 1945 until his death in 1952. He was a member of the Democratic Party and played a significant role in post-World War II legislation, focusing on issues such as national security and civil rights. McMahon is perhaps best known for his work on the Atomic Energy Act of 1946, which established the framework for the peaceful use of atomic energy. His efforts contributed to the development of the Atomic Energy Commission, which regulated nuclear energy and research in the United States.