What qualities did many Progressive reformers share?

The question could safely be rephrased to ask, 'What Qualities Did the Few Progressive Reformers Share?'. Because, frankly there have not been that many "progressive reformers" successful enough to be notable.

And it is remarkable that two of the the most famous, and effective, reformers are of the same last name. In fact, related.

Theodore Roosevelt, first cousin to the later President Franklin D. Roosevelt. Both men rewrote the financial playbooks for their time. Both had radical, unpopular approaches to taming an out of control financial market system. Both were highly successful. Teddy Roosevelt established the National Park Service. He saved many famous landmarks from destruction by land speculators, by declaring them "National Monuments" when congress refused to declare them part of the National Park Service.

It is of course a matter of opinion, but other than these two men, each with very competitive, massive egos and a populist agenda are virtually unique among progressive reformers. And one, Theodore, was a republican.