Grete Waitz, née Grete Andersen, (1 October 1953 – 19 April 2011) was a Norwegian marathon runner and former world record holder. In 1979, at the New York City Marathon, she became the first woman in history to run the marathon in under two and a half hours. Waitz won nine New York City Marathons, women's division, between 1978 and 1988, the highest number of victories in a single big city marathon in history. She won the silver medal at the 1984 Olympic Games in Los Angeles and a gold medal at the 1983 World Championships in Helsinki. She was also a five-time winner of the World Cross Country Championships.

Waitz four times set a world record in the marathon, twice at the 3000 metres, and she set world records at distances of 8 kilometers, 10 kilometers, 15 kilometers and 10 miles. She won 12 World Marathon Majors, the most for any runner, earning her a place in the Guinness World Records. Her other marathon victories included winning the London Marathon in 1983 and 1986 and the Stockholm Marathon in 1988.

Born Grete Andersen in Oslo, Norway, Waitz was a talented young runner, but had difficulty in getting her parents to take her potential profession seriously. However, she ran at the 1972 Summer Olympics in Munich in the 1500 metres, and to support her athletic career she studied at a teachers college.^{[citation needed]}

In her teen years, Andersen won national junior titles in Norway in the 400 and 800 metres. At age 17, she set the European junior record for the 1500 metres with a time of 4:17 and won the bronze medal at the European Athletics Championships in this event in 1974. Andersen won the British WAAA Championships title in the 1500 metres event at the 1974 WAAA Championships.

In 1975, Waitz broke the 3000 metres world record, running 8:46.6 in Oslo. Also in Oslo a year later, she lowered this record with an 8:45.4 effort, then in 1977 she won the gold medal over the distance at the inaugural IAAF World Cup in Athletics meet in Düsseldorf with a personal best time of 8:43.50. Two years later in Montreal, she won the silver medal, and came to her all-time personal best of 8:31.75 in Oslo.

She ran the 1500 m at the European Championships in Prague on 3 September 1978. The run was won by Giana Romanova (USSR) in 3:59.01. Waitz placed fifth, with a career best of 4:00.55. It still stands as the Norwegian national record. Back then it was the eighth best time for the 1500 m. On 29 August at the Championships, she placed third in the 3000 m, with a time of 8:34.33. The winner was Svetlana Ulmasova with 8:33.16.

It was in 1978 that Waitz' association with the New York City Marathon began; she was invited to run there by race co-founder and director Fred Lebow, and in her first appearance, she not only won but took a full two minutes off the women's course record. On 22 October 1978, she finished in 2:32:30 more than 9 minutes ahead of Marty Cooksey's 2:41:49. Cooksey won the San Diego Half Marathon on 26 Aug in 1:15:04. Waitz' winning time there was a world record. During 1978, the world record in the women's marathon was 2:34:47.5 set on 10 September 1977 by Christa Vahlensieck at the Berlin Marathon. In 1981, the 1978 NYC course was remeasured and found 151 meters short. She further improved her NYC record with her following victories in 1979 and 1980.

According to the Association of Road Racing Statisticians (ARRS) Waitz had a 28 race winning streak from 22 September 1979 with a win in a 10-mile road race in Lynchburg (USA) until 8 June 1981 her win in a 3000 m track race in Basel (Switzerland).