Ivan Lendl (Czech pronunciation: [ˈɪvan ˈlɛndl̩]; born March 7, 1960) is a Czech–American former professional tennis player. He is widely regarded as one of the greatest tennis players of all time. Lendl was ranked world No. 1 in singles for 270 weeks and won 94 singles titles. He won eight major singles titles and was runner-up a joint record 11 times (tied with Roger Federer and Novak Djokovic), making him the first man to contest 19 major finals. Lendl also contested a record eight consecutive US Open finals, and won seven year-end championships.

Lendl is the only man in professional tennis history to have a match winning percentage of over 90% in five different years (1982, 1985, 1986, 1987, and 1989). He also had a comfortable head-to-head winning record against his biggest rivals, which translates to a 22–13 record (4–3 in major matches) against Jimmy Connors and a 21–15 record (7–3 in major matches) against John McEnroe.

Lendl's dominance of his era was the most evident at the year-end championships, which feature the eight best-ranked singles players. He holds a win–loss record at the event of 39–10, having contested the final nine consecutive times, a record.

Commonly referred to as the 'Father Of Modern Tennis' and 'The Father Of The Inside-Out Forehand', Lendl pioneered a new style of tennis; his game was built around his forehand, hit hard and with a heavy topspin, and his success is cited as a primary influence in popularizing the now-common playing style of aggressive baseline power tennis. After retirement, he became a tennis coach for several players; in particular, he helped Andy Murray win three major titles and reach the world No. 1 ranking.