Winston Churchill, Prime Minister of Britain, played a pretty massive role in Britain's part in WWI. He led Britain to victory twice during the war. A very great Prime Minister on Britain's part, without him, they probably wouldn't have done what they did in the war. He also warned his men of the nationalism that Germany was proposing. If Germany got too full of themselves, they could try to go to war with other countries, and Churchill didn't want to be surprised, he wanted the people, including himself, to be prepared for whatever could happen next.
Woodrow Wilson was the 28th President of the United States, being best known for his role in WWI. He kept the US out of the war until 1917, and he also came up with the 14 points. The points talked about Freedom of the Seas, Arms reduction, etc. The 14 points paved the way to what America is today, and the country would be a lot different if it wasn't for these 14 points.