Margaret Keyes Groos (born September 21, 1959) is a retired long-distance runner from the United States.
Groos was born and raised in Nashville, Tennessee, where she graduated from Harpeth Hall School in 1977. As a ninth grader, she set the national record for the 880 yard run (2:10.06). As a senior, she set a state record in the 1600 meters (4:45.44) that wasn't broken for 40 years.[1] Overall, she won state championships in the 880 yard and the mile run three times, each, while being part of a state champion mile relay and twice being part of Harpeth Hall's state championship team (and being part of their runner-up team another year).[2][3]
She was recruited to the University of Virginia. In 1981, she set a world indoor record for the 5000 meter run.[4][5]
Groos competed in the marathon at the 1988 Summer Olympics in Seoul, Korea, and was an alternate for the 1984 Olympic Games. She twice won the Pittsburgh Marathon, including in 1988, when she ran her personal best and the course record for females (2:29:50).