Michael Reagan, the eldest son of former U.S. President Ronald Reagan, has died at the age of 80. The Ronald Reagan Presidential Foundation and Institute announced his passing, remembering him as a "steadfast guardian of his father's legacy." Reagan was a conservative commentator, author, and radio talk show host who dedicated much of his public life to promoting his father's ideals. He also engaged in various charitable activities and had a career in acting. His cause of death was not immediately announced.