Marta Kostyuk (born June 2002) is a Ukrainian professional tennis player who has risen to a career-high WTA ranking of No. 11, currently making her the No. 2 player from Ukraine. Her major career highlights include winning three WTA singles titles, most notably the 2026 Madrid Open, and reaching the semifinals at both the 2026 French Open and 2026 Wimbledon Championships. She first made international headlines at the 2018 Australian Open when, at just 15 years old, she qualified for the main draw and became the youngest player to win a match in Melbourne since Martina Hingis in 1996. Before turning pro, she showcased immense talent as a junior, winning the girls' singles title at the 2017 Australian Open and the girls' doubles title at the 2017 US Open. Coming from a tennis family, her mother was a professional player, and Kostyuk originally took up the sport just to spend more time with her; she married her fiancé Hryhoriy in 2023.