Today we are inundated with conspiracy theories, but the widespread proliferation of lies and misinformation can make it easy to forget that conspiracy theories have been part of American life from the beginning. Conspirator in Chief is a tour through the Hall of Shame in American politics. Thomas Jefferson used surrogates to spread false claims about Alexander Hamilton, attacked newspaper editors who were critical, and used conspiracy theories about the Federalists to tarnish them. This brand of demagoguery reached an apex in the presidency of Andrew Jackson, who publicly defamed abolitionists, manipulated newspapers, and spread his own "Big Lie" about the 1824 election being stolen from him. Andrew Johnson spread false accusations about the Radical Republicans and made spurious claims about the dangers of a coming Black supremacy. Woodrow Wilson continued Johnson's racist and conspiratorial interpretation of American history. Knott also uncovers the conspiratorial inclinations of our more esteemed leaders, including Franklin Delano Roosevelt and Harry S Truman. Knott shows how both presidents painted their opponents in an extreme light, casting aspersions on political rivals by calling them "betrayers of America," and comparing them to Nazis, fascists, and communists. Less surprising are the presidencies of Richard Nixon and Donald J. Trump, both known for their propagation of racist and paranoid beliefs and their denigration of political opponents. While Trump is in a league of his own regarding the sheer output and outlandishness of his conspiracy-mongering, he did not begin this odious practice. Knott does more than show how low American presidents have gone. He also illuminates an alternative track record in which presidents took the high road. Conspirator in Chief is a sobering reminder of the power of a president's words and the damage they can do, but it is also a reminder that words can heal and repair as well.