Trump hasn't had enough time to see what his impact on the world will be. For me it's Steve Jobs and Bill Gates. Personal computers and cell phones changed everything.
It is not a person. It is the loss of inalienable rights with knuckleheads supporting it. Which also incorporates the use of surveillance technology on all of us including the ones who use it. And the people who use it against others being the true knuckleheads. Being inept and incompetent makes it worse. This site proclaims to be self sealed with the people who are members spouting their views. But in all likelihood we are monitored by the knuckleheads of the surveillance realm trying to detect those who are against the fiefdoms they rule over. Some may even be members. Freedom is precious. And we gave a lot of it up without a shot fired. A comfortable life can mask the loss of rights. The 21st century will be remembered for the knuckleheads who let the freedoms become a tenuous thing. But we have our security. Nazi Germany and the Soviet Union and so many others had security also.
Franklin Delanor Roosevelt, hands down. Global influence not seen since the British Empire of the 19th Century, completely changed the face of politics domestic and foreign. With the exception of Jesus, whether real or fictional makes no difference, FDR was more influential than any on the list. Most of the rest were merely tools or criminals or both. Anybody who doubts FDR has any influence in the 21st Century needs to go back to school and finish the 8th grade at least.