Infobox last updated on: 15 May 2008.

Justine Henin (known as Justine Henin Hardenne 2002–2007), (born 1 June 1982) is a retired professional Belgian tennis player. On 14 May 2008, Henin announced her immediate retirement from professional tennis. She was 25 years old and ranked World No. 1 at the time of her retirement. Billie Jean King has said that "pound for pound, Henin is the best tennis player of her generation."

Henin won 41 WTA singles titles and more than US$19 million in prize money. Seven of those titles were Grand Slam singles titles, including four French Open titles, one Australian Open title, and two US Open titles. She also won the year-ending Sony Ericsson Championships twice and the singles gold medal at the 2004 Summer Olympics. Tennis experts cite her mental toughness, the completeness and variety of her game, her footspeed and footwork, and her one-handed backhand (which John McEnroe has described as the best single-handed backhand in the women's or men's game ) as the principal reasons for her success.