Alex T. Michelsen (born August 25, 2004) is an American professional tennis player who reached a career-high ATP singles ranking of world No. 30 in July 2025. As a junior, he won the boys' doubles title at Wimbledon in 2022 and swept the singles and doubles titles at the Easter Bowl, a feat not achieved by an American since Donald Young in 2006. Turning pro in 2023, he made an immediate impact by reaching his first ATP final at the Hall of Fame Open in Newport, becoming the youngest American to do so since Taylor Fritz, and later made his Grand Slam debut at the US Open. In 2024, he advanced to the third round of the Australian Open and recorded his first top-10 victory by defeating Alex de Minaur at the Los Cabos Open. His rapid rise culminated in a top-30 ranking in 2025, solidifying him as one of the most promising young talents in American tennis.