Alexi Singh Grewal (ਅਲੇਕ੍ਸੀ ਸਿੰਘ ਗਰੇਵਾਲ ) (born September 8, 1960 in Aspen, Colorado) is a Sikh-American Olympic gold medalist and former professional road racing cyclist. At the 1984 Summer Olympics in Los Angeles, Grewal became the first American man to win an Olympic gold medal in road cycling. His winning bicycle is now at the Smithsonian Institution's National Museum of American History. He has two brothers, Rishi and Ranjeet, who were also top American cyclists, especially in mountain bike racing.

The U.S. Bicycling Hall of Fame gave the following description of his Los Angeles gold medal ride: "With an estimated crowd of 300,000 lining the 190.2-kilometer route, Grewal edged Canadian Steve Bauer to claim the gold medal in the men's road race, breaking away from the field with 20 kilometers remaining and opening up a 24-second lead after 11 of 12 laps and then being caught by Bauer with 10 kilometers left, setting up a dramatic final-lap showdown. This scene, replayed many times since, is one of the most emotional Olympic victories of the Modern Games."