Marion Lois Jones, also known as Marion Jones-Thompson (born October 12 1975 in Los Angeles, California), is a former American track and field athlete of Belizean descent. She won five medals at the 2000 Summer Olympics in Sydney, Australia but has since been stripped of every medal dating back to September 2000 after admitting that she took performance-enhancing drugs.

In October 2007, Jones admitted to having taken steroids before the Sydney 2000 Summer Olympics and acknowledged that she had, in fact, lied when she previously denied steroid use in statements to the press, to various sports agencies, and--most significantly--to two grand juries, one impaneled to investigate the BALCO "designer steroid" ring, and the other impaneled to investigate a check fraud ring involving many of the same parties from the BALCO case. As a result of these admissions, Jones accepted a two-year suspension from track and field competition, and announced her retirement from track and field on October 5, 2007. The United States Anti-Doping Agency stated that the sanction “also requires disqualification of all her competitive results obtained after September 1, 2000, and forfeiture of all medals, results, points and prizes”. On October 5 2007, Jones formally pled guilty to lying to federal agents in the BALCO steroid investigation in the U.S. District Court.

At the time of her admission and subsequent guilty plea, Marion Jones was one of the most famous people to be linked to the BALCO investigation. Just 41 days later, Major League Baseball player Barry Bonds was indicted on one count of obstruction of justice and four counts of perjury linked to his own testimony before the BALCO Grand Jury in December of 2003.

Marion Jones Farquhar (born November 2, 1879 in Gold Hill, Nevada, USA - March 14, 1965) is a former American female tennis player. She is best remembered for winning the women's singles titles at the 1899 and 1902 U.S. Championships.

She was inducted into the International Tennis Hall of Fame in 2006.