The Austro hungarian empire was run by Franz Josef. This was an autocracy in the old style, and it was here, or rather in sarajevo, that the war started. This is a historically interesting one as he was the last ruler who could claim to be the Holy Roman Emperor, and a direct descendant (in a way, anyway) of cvharlemagne. The habsburgs also claimed to be related to Jesus, but lots of people claim this sort of thing.
The French were run by an elected primeminister: they had a few over the years but I believe Clemenceau was the most notable. He certainly came up with the best quote of the war. When Told that Woodrow Wilson was coming from america with his 14 points for peace he exclaimed "God Almighty only had 10".
We were run by two liberal prime ministers, first Herbert Asquith, then (after he had stabbed Asquith in the back) Loyd George, who could claim with osme justification to have won the war. Japan was run by an emperor, and they were on our side for a change.
The Canadians, I think it was Mackenzie King, wasnt it? Some help from the maple leaves out there?