Mary Teresa Slaney (formerly Tabb, nee Decker; born August 4, 1958) is a retired American middle-distance runner. During her career, she won gold medals in the 1500 meters and 3000 meters at the 1983 World Championships, and was the world record holder in the mile, 5000 meters and 10,000 meters. In total, she set 17 official and unofficial world records, including being the first woman in history to break 4:20 for the mile. She also set 36 US national records at distances ranging from 800 meters to 10,000 meters, and has held the US record in the mile, 2000 meters and 3000 meters since the early 1980s, while her 1500 meters record stood for 32 years.

Decker was heavily favored to win a gold medal in the 3000 meters run at the 1984 Summer Olympics, held at Los Angeles. In the final, Zola Budd, representing Great Britain, had been running barefoot side by side with Decker for three laps and moved ahead. In an attempt to put pressure on Budd, Decker remained close by in a crowded space. Decker stood on Budd, then shortly after, collided with the barefoot runner and fell spectacularly to the curb. As a result, Mary Decker did not finish the race, which was won by Maricica Puica of Romania (Budd finished seventh). Decker was carried off the track in tears by her boyfriend (and later, husband), British discus thrower Richard Slaney. At a press conference she said that Budd was to blame for the collision. While it is generally the trailing athlete's responsibility to avoid contact with the runner ahead, it is also an accepted convention among most distance runners that the leader be a full stride ahead before cutting in. Track officials initially disqualified Budd for obstruction, but she was reinstated just one hour later once officials had viewed films of the race. Despite being behind Budd, Decker's claim that Budd had bumped into her leg was supported by a number of U.S. sports journalists, and Budd was hounded constantly in the press as a result, receiving a number of death threats. The claim was never accepted by the director of the games or the IAAF.  Decker and Budd next met in July 1985, in a 3000 meters race at Crystal Palace National Sports Centre in London, England. Decker won the race, and Budd finished in fourth place. After the race, the two women shook hands and made up. Decker later went on record as claiming that she was unfairly robbed of the LA 3000 meters gold medal by Budd, but said many years after the event "The reason I fell, some people think she tripped me deliberately. I happen to know that wasn't the case at all. The reason I fell is because I am and was very inexperienced in running in a pack."  Decker had a successful 1985 season, winning twelve mile and 3000 meters races in the European athletics calendar, which included a new official world record for the women's mile of 4:16.71 in Zurich (Natalya Artyomova's 4:15.8 in 1984, not being ratified by the IAAF). Since that race in 1985, her time has only been bettered on four occasions. That race in Zurich also matched her with both of the other principle athletes from the Olympic race, Slaney vanquishing both Puica and Budd who themselves ran times that until July 9, 2017 also ranked in the top 10 of all time.  She sat out the 1986 season to give birth to her only child, daughter Ashley Lynn (born May 30, 1986), but missed the 1987 season due to injury. She qualified for the 1988 Summer Olympics in Seoul, South Korea, but failed to win a medal. She did not qualify for the 1992 Games.

Did she participate in any other events that olympics?
Decker had a successful 1985 season, winning twelve mile and 3000 meters races in the European athletics calendar,