#1 Shizo Kanakuri (1912 Stockholm Games)
Perhaps the best one on this list, the Japanese marathon runner disappeared during this race in the 1912 games. It was later known that runner lost consciousness due to the severe heat conditions (many participants also collapsed) and was cared by a local family. Embarrassed by his failure Kanakuri returned to Japan without telling the officials who of course listed him as officially missing.
Although he did later compete in the 1920 and 1924 games, it wasn’t until the mid-1960 that the Swedish officials knew that he was alive and offered him to complete the marathon; an offer he accepted. He completed the marathon in 1967 clocking a final time of 54 years, 8 months, 6days, 5 hours, 32 minutes and 20.379 seconds.