Henry Nicholas John Gunther (June 6, 1895 – November 11, 1918) was an American soldier and likely the last soldier of any of the belligerents to be killed during World War I. He was killed at 10:59 a.m., about one minute before the Armistice was to take effect at 11:00 a.m.
Sorry for the pedantry, but almost for sure not the last. This just doesn't work this way. Humans aren't robots to furiously fight till 11.00 a.m. and happily relax at 11.01 a.m. There surely were skirmishes which lasted some time after the official armistice. If someone just killed your brother in arms and then appearing from the trenches one minute later, you'll likely kill the bastard: "yes, sir, my watch is a little behind..."