Lydia Ko (Korean: 고보경, Hanja: 高寶璟, born Bo-kyung Ko, 24 April 1997) is a New Zealand professional golfer who became the No. 1 ranked woman professional golfer on 2 February 2015 at 17 years 9 months 8 days of age, making her the youngest player of either sex to be ranked No. 1 in professional golf. On 13 September 2015, she became the youngest woman, at age 18 years, 4 months and 20 days, to win a major championship when she won The Evian Championship in France.