Nancy Jane Ditz (born June 25, 1954 in San Jose, California) is a former American long-distance runner who is a United States national champion in the marathon. Ditz competed in the marathon at the 1988 Summer Olympics. In her debut marathon, Ditz won the 1982 San Francisco Marathon (2:44:34). She also set a course record at the 1985 California International Marathon with a time of 2:31:36. Nancy worked to promote the 2009 Los Angeles Marathon with fellow Olympians Rod Dixon and Ed Eyestone.