Martti Vainio, Finnish runner
Martti Olavi Vainio (born 30 December 1950) is a Finnish former long-distance runner. In Finland he is recognized as the last of the great runners of the famous "V-line", the previous ones being Juha Väätäinen, Lasse Virén, and Pekka Vasala. Each of them won at least one gold medal either at the Summer Olympics or the European Athletics Championships in the 1970s. Vainio's accomplishments are tarnished though, for testing positive for PEDs on at least two occasions. One of those events was the 1984 Olympic Games where he was disqualified and stripped of his medal and later suspended from sport.

His achievements in major athletic championships include gold in the 10,000 metres race 1978 European Championships in Athletics in Prague and bronze in the same distance at the 1982 European Championships in Athletics in Athens. At the 1983 World Championships in Athletics he dropped to fourth place in the 10,000 metres race, but claimed the bronze in the 5000 metres in a close finish decided by a lunge over the finish line.