Mary Terstegge Meagher Plant (born October 27, 1964) is an American former swimmer, Olympic champion, and world record-holder. In 1981 she bettered her own existing world records in the 100-meter butterfly (57.93) and 200-meter butterfly (2:05.96). These times that would stand as the respective world records for 18 and 19 years, and are considered to be among the greatest sports performances ever.
However, in 1981 Meagher gave one of the most memorable performances in competitive swimming at the U.S. Swimming National Championships held in Brown Deer, Wisconsin in 1981. At the meet, Meagher set world records in both the 200-meter and 100-meter butterfly, the two primary distances at which the butterfly is contested in competitive swimming. The times for both records were considered astonishing, especially the record of 57.93 seconds that Meagher set in the 100-meters—a drop of over a second. Both times would stand as the World Record for nearly two decades: American swimmer Jenny Thompson lowered the 100-meter record in 1999, while Susie O'Neill of Australia set the record in the 200-meter a year later. Some have argued that Meagher's records in the butterfly were among the most impressive records ever set in sport, let alone swimming, ranking among such noteworthy records as Bob Beamon's long jump world record in 1968. These two swims led Meagher to being named Female World Swimmer of the Year by Swimming World magazine, which she again won in 1985. She swam collegiately for the University of California, Berkeley, graduating in 1987 with a Bachelor of Arts degree in social sciences.