The 1908 Olympics Men's 400m final was run by a single competitor, making it the only "walkover" final in Olympic history.

The lucky man was Wyndham Halswelle, and was a Briton who lived from 1882 to 1915. During the 1908 Summer Olympics, Halswelle reached the final of the 400 meter dash with the fastest qualifying time, an Olympic record of 48.4 seconds. 

At this time, the 400 meter dash wasn’t run in lanes, making it more of a competition based on blocking and passing the other runners than one of a race against time. Halswelle was at first behind William Robbins, who was leading John Carpenter by a yard.

John Carpenter forced Halswelle to within 18 inches of the track’s edge, and used his elbow to keep Halswelle from passing him. The umpire called a foul, and the race was declared void. The race to be rerun in lanes two days later without Carpenter, but the two other runners refused to race again, so Halswelle ran by himself to win the gold in a time of 50.2 seconds. 

Due to this event, lanes have been used since 1912. Halswelle went on to fight in World War I, where he was killed by a sniper at the Battle of Neuve Chapelle in France.

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