Oscar Larsen was a Norwegian

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 middle distance runner. He represented Kristiania IF.

Participating at the 1908 Summer Olympics

1908 Summer Olympics

The 1908 Summer Olympics, officially the Games of the IV Olympiad, were an international multi-sport event which was held in 1908 in London, England, United Kingdom. These games were originally scheduled to be held in Rome. At the time they were the fifth modern Olympic games...

, Larsen placed fourth of seven in his initial 1500 metres

Athletics at the 1908 Summer Olympics - Men's 1500 metres

The men's 1500 metres was an Olympic event for the fourth times at the 1908 Summer Olympics. The competition was held on July 13, 1908 and on July 14, 1908. The races were held on a track of 536.45 metres= mile in circumference...

 semifinal heat and did not advance to the final. At the 1912 Summer Olympics

1912 Summer Olympics

The 1912 Summer Olympics, officially known as the Games of the V Olympiad, were an international multi-sport event held in Stockholm, Sweden, between 5 May and 27 July 1912. Twenty-eight nations and 2,407 competitors, including 48 women, competed in 102 events in 14 sports...

he participated in both 800 and 1500 metres, without reaching the final. He became Norwegian champion in the 800 metres in 1911 and 1914 and in the 1500 metres in 1911, 1914 and 1915.