Can the actions of one person change history?

There was once a theory, called “The Great Man” theory, that argued that a single dynamic person changed the path of history by himself – Hitler, Alexander, Stalin, Caesar, etc. But more modern theories maintain that the social and political milieu is what really makes the path of history, and that the “great man” is merely the instrument that history follows to give focus to the historical narrative. For example, Stalin moved Russian history in a certain direction because serfdom had collapsed (see Elias Canetti’s Crowds and Power), or slavery was abolished during Lincoln’s presidency but not because of Lincoln himself. So while it is true that history is in part the biography of great persons, one man’s effect on history’s path is exaggerated. It is true that random individuals (Lee Harvey Oswald, John Wilkes Booth) can interrupt the path of history. Another exception might be technological innovators, such as Henry Ford, Thomas Edison, or Galileo.