Dean Acheson: one of our most beloved historical figures and Cold War heroes today, right?
(Confession: it's totally okay for you to be looking confused right now and asking "Dean Who?" because most people don't know who he is either. But we're here to fix that.)
As Undersecretary of State, Dean Acheson was a primary author of two of the most important texts in early Cold War history—the official Marshall Plan legislation and our own Truman Doctrine. In some ways, the names of both texts could be replaced with "Acheson," especially if you want to give a proper shout-out to the guy who wrote and reviewed the most drafts of each. (Note: this is also the person who suggested not mentioning the Soviet Union by name in the speech because it would limit the document's power if some other threat with a different name emerged. Smart, huh?)
Acheson was probably the most influential advisor in Truman's cabinet. They saw each other at least twice a week and talked on the phone almost every day, for goodness' sake. (They probably also ate brunch together, checked each others' outfits before they went out, and played M*A*S*H*. It was an epic bromance.)
His staunch views on foreign policy in particular had an effect on Truman, and can be seen in both the president's doctrine as well as Truman's decision to send troops to Korea. Both men understood the gravity of the Soviet threat and, as Acheson put it, they saw their recommendations as defining not just U.S. policy, but "world" policy for the Cold War in which the world was now engaged. (Source)
Hogwarts House: Ravenclaw: super smart and dedicated to his work, reserved/not necessarily the life of the party, somewhat eccentric appearance (giant mustache).