This makes me feel old, as Mulroney was a fixture of the Western alliance of the 1980s that won the Cold War, which I remember from when I was growing up. The others (Reagan, Margaret Thatcher, and Helmut Kohl) have all passed away previously.
On a more substantive note, all Americans and Canadians should be grateful to Mulroney for negotiating (with Reagan) the US-Canada free trade agreement, which has made both countries significantly freer and wealthier than they would be otherwise. He overcame a lot of domestic opposition to do it. We could use some of Mulroney's (and Reagan's) commitment to free trade today, as both major US parties have gone badly wrong on that issue.