Heidemarie Ecker-Rosendahl (born 14 February 1947) is a retired German athlete who competed mainly in the pentathlon and long jump. She set a world record in the long jump at 6.84 m in 1970 that stood for almost six years.
She won the long jump gold medal in the 1972 Munich Olympics with a leap of 6.78 m, one centimetre ahead of Diana Yorgova of Bulgaria. Two days later in a thrilling pentathlon, she finished second to Mary Peters of Britain.
After the three events on the first day Rosendahl was in the fifth place, 301 points behind Peters. On the second day, she jumped 6.83 m in the long jump (one cm short of the record) and ran the 200 m in 22.96 seconds. She finished with 4791 points, 16 points better than Burglinde Pollak's world record. She held the world record for 1.12 seconds before Peters bettered it by 10 points on finishing her 200 m race in 24.08 seconds. To further prove her versatility, she helped the West German 4 × 100 m team with Christiane Krause, Ingrid Mickler-Becker and Annegret Richter to the gold medal and a world record; holding off the East German sprints champion Renate Stecher, in the process.
In 1970 and 1972 Rosendahl was chosen as the German Sportswoman of the Year. She had a degree in physical education and worked as athletics coach at TSV Bayer 04 Leverkusen (1976–1990) and Deutsche Leichtathletik-Verband (1993–2001). She is married to John Ecker, an American basketball player who won the 1969, 1970 and 1971 NCAA Championships as a member of the UCLA Bruins. Their son, Danny Ecker, is a world-class pole vaulter. Rosendahl's father, Heinz Rosendahl, was the German champion in the discus throw in 1948, 1951 and 1953.