Thierry Ascione (; born 17 January 1981) is an ATP tennis coach and a former professional player from France. He reached a career-high singles ranking of World No. 81 in February 2004.
Ascione turned pro in 2000. He played Roger Federer in the second round of Roland Garros 2007, saving five match points in the third set and holding two set points before eventually losing in straight sets.
He retired in September 2010 and was the tournament director of the defunct ATP Lyon Open, and later following its cancellation, currently director of the All In Open Challenger.
Since his retirement he coached the former World No. 3 WTA player, Elina Svitolina. He was also coach to former World No. 5 ATP player Jo-Wilfried Tsonga and former World No.7 Richard Gasquet.
Since 2021 he coached Ugo Humbert (until 2022) and also Lucas Pouille (until 2024)