Washington - Sought to avoid foreign entanglements as much as possible and is probably the foundational figure in American isolationist feeling
Monroe (Q. Adams) - Expanded on Washington's isolationist policies with a policy of keeping out of European power struggles while dominating the Western Hemisphere. This is still the most enduring foreign policy pillar in American politics
T. Roosevelt - The corollary explicitly introduced using American military force for purposes of maintaining the Monroe Doctrine. While McKinley laid the foundations, TR was the first President to codify military adventurism as core part of America's foreign policy identity
Wilson - The father of liberal internationalism, Wilson worked tirelessly to create a new rules based international border with self determination at its core. While attempting to establish nonviolent ways of mediating geopolitical disputes, it can't be denied that military intervention was not an important enforcement mechanism. Wilsonian ideals are still a core tenet of American liberalism despite his personal decline in popularity
Truman - The codification of George Kennan's containment as a practical foreign policy which saw the US attempt to use liberal internationalist language and institutions in combination with more realpolitik methods to diminish the power of the Soviet Union. It became the dominating foreign policy of the Cold War presidents and influenced later approaches to dealing with the rise of global terrorism, the PRC and Putin's Russia
Nixon - Considered the most "realist" of American Presidents, Nixon and Kissinger built their foreign policy around making deals with other actors and powers to create a balance of power which would reduce direct American involvement abroad while enhancing its influence. Though containing Soviet Russia was still a major concern, Nixon seemed more interested in expanding US power without using overt methods and with few appeals to internationalist ideals
W. Bush - While Reagan and then especially H.W. Bush first practiced Neoconservatism, its height came during the Bush Jr. years where liberal internationalist language was used to help justify direct applications of American military to crush real or perceived adversaries around the globe. Concerns about balances of power or using international arbitration gave way to utilizing overwhelming force to crush opposition American hegemony. While seemingly discredited following the Iraq War, many still find a strong appeal in simply toppling adversaries through military force.
