The actor who served as the 40th President of the United States was Ronald Reagan. Before his presidency, he was a prominent Hollywood actor and served as the Governor of California. Reagan’s presidency, from 1981 to 1989, was characterized by significant political events such as the Cold War dynamics, tax reforms, and social conservatism. He is often credited with revitalizing the American economy and promoting deregulation, which had lasting effects on U.S. politics and society.