Jacqueline ("Jacki") Hansen (born November 20, 1948) is a former long-distance runner from the United States who is recognized by the International Association of Athletics Federations as having set a world best in the marathon on two different occasions.
Hansen set a world best mark on December 1, 1974, with a 2:43:55 performance at the Western Hemisphere Marathon in Culver City, California, then recaptured it from Christa Vahlensieck of West Germany on October 12, 1975, with 2:38:19 at the Nike OTC Marathon in Eugene, Oregon. With these two performances, she was ranked first in women's marathon for 1974 and 1975.
Hansen won 12 of her first 15 marathons. Among these victories, she won the prestigious Boston Marathon in 1973, the Honolulu Marathon in 1975, and the Avenue of the Giants Marathon in 1976. Hansen is also a three-time winner of the Western Hemisphere Marathon (1972, 1974, 1977) and the Catalina Marathon (1979, 1981, 1982).
At the 1987 World Masters Athletics Championships in Melbourne, Australia, Hansen won titles in the 1,500 meters and the 5,000 meters.
Hansen was the president of a group, the International Runners Committee, that successfully lobbied the International Olympic Committee to add women's events for the 5,000 meters, the 10,000 meters, and the marathon.