Darren Cahill, born in Adelaide on 2 October 1965, is an Australian tennis coach and former tennis player.
After retiring he remained in the tennis environment as a coach and led Lleyton Hewitt to become the youngest ever to reach the first position of the ranking, subsequently he collaborated with Andre Agassi, who under his guidance became the oldest number one of the world in May 2003.
After Agassi's retirement in 2006 he entered the Adidas Player Development Program for which he followed Andy Murray, Ana Ivanović, Fernando Verdasco, Daniela Hantuchová, Sorana Cirstea and Simona Halep, whom he has coached since 2017 to 2018 helping her to reach the first position of the WTA rankings.
At the end of the 2018 season, he interrupted his working relationship with the Romanian tennis player to devote more time to his family. But at the beginning of 2020 he resumed his coaching job with Simona Halep
From 2007 to 2009 he was also captain of the Australian Davis Cup national team.
In June 2022 he was announced as supercoach in the team of Italian tennis player Jannik Sinner.