Lasse Virén (born July 22, 1949) is a former Finnish athlete, winner of four gold medals at the 1972 Summer Olympics and 1976 Summer Olympics.

Born in Myrskylä, Finland, Lasse Virén recaptured the image of the "Flying Finns" promulgated by runners like Hannes Kolehmainen, Paavo Nurmi, and Ville Ritola in the 1920s.

A police officer from Myrskylä, Virén debuted on the international scene in 1971. At the 1972 Summer Olympics at Munich, Virén won both the 5000 meters and the 10,000 meters, setting a world record despite falling in the latter event. He became the fourth athlete to win both events in the same Olympics, joining Hannes Kolehmainen (1912), Emil Zátopek (1952), Volodymyr Kuts (1956) and, after them, as a fifth (and last) Miruts Yifter (1980).

Virén ran with success between the Olympics. At the 1976 Summer Olympics, Virén again won both events, becoming the repeat winner of the 5000 meters race. His wins were not without controversy. First, in the 10,000 meters, he carried his shoes with him on his victory lap. The International Olympic Committee accused Virén of malicious intent, such as showing the logo on the shoes, but he explained that he had a blister. Additionally, Virén was involved in the then-legal practice of blood boosting which involved freezing blood then having it returned to the body later to improve the oxygen content.

Lasse Virén ended his career after the 1980 Summer Olympics, where he placed fifth in the 10,000 meters.

Since his career ended, he has become a well known figure in Finland, even winning a seat in the Finnish Parliament.