Harilaos Vasilakos became the first winner to win the official marathon and later won silver during the 1896 Olympic Games at the marathon. The first marathon during the Olympic Games in 1896 was won by Spiridon Luis, but it is unlikely that one could bypass Harilaos Vasilakos' silver medalist.

Vasilakos was born in Piraeus, Greece. At a young age he studied law at the University of Athens and worked at the Athens Court. Vasilakos was also a member of the Panellinios sports club where he practiced running.

On March 22, 1896, a classification marathon took place in Greece, where participants were selected for the team that would represent the country at the 1896 Olympic Games. Since Vasilakos had a reputation as a strong long-distance runner, he participated in winning it with a time of 3 hours 18 minutes.

On April 10, 1896, Vasilakos was one of the athletes who ran the marathon during the 1896 Olympic Games. He was among the leaders of the marathon, but when the leaders began to fall out, he became a favorite of the marathon. At the end of the marathon, he was overtaken by his countryman Spiridon Luis, who then won the marathon, and Vasilakos finished the marathon with a time of 03: 06.03 and finished second.

After the Olympics, Vasilakos was involved in the promotion of sports walking in Greece, and between 1900 and 1906 participated in several races.

In 1960, King Paul of Greece awarded him the Order of the Phoenix. The annual marathon competitions held in Olympia honor Vasilakos' memory.

In 2012, a book was published about Harilaos Vasilakos as an athlete.