Tai Tzu-ying (Chinese: 戴資穎; pinyin: Dài Zīyǐng; Wade–Giles: Tai Tzu-ying; born 20 June 1994) is a Taiwanese retired professional badminton player. At the age of 22, she achieved world no.1 ranking in December 2016, and held that position for 214 weeks in different spells, second longest in the BWF women's singles history. Tai was the women's singles silver medalist in the Tokyo 2020 Olympics and the 2021 BWF World Championships. She was gold medalist in the 2017 Summer Universiade and the 2018 Asian Games. She was the champion of BWF Super Series Finals/BWF World Tour Finals a record four times (2014, 2016, 2020, 2023). She was thrice the champion of the All England Open (2017, 2018, 2020), and of the Asian Championships (2017, 2018, 2023).

Tai's career began when she was in elementary school, as she was influenced by her father who was a firefighter and the director of Kaohsiung city's badminton committee. Tai started playing badminton in the fourth or fifth grade of elementary school, and in the sixth grade, she played at the National ranking tournament, won the title in the second division, and earned the right to participate in the first division games. She was the youngest player to compete in the first division.

Tai made her debut in an international tournament in 2007 at the Vietnam International. In 2009, she won the silver medal at the Asian Junior Championships, losing the final match to Chen Xiaojia in straight games. She represented Kaohsiung City in the National Games and went on to the quarter-finals. Young Tai began to show her potential when she was 15 years old, as she was able to compete at the senior level and become runner-up at the Vietnam Open, a Grand Prix tournament. In December, Tai competed at the East Asian Games for Chinese Taipei, won a bronze medal in the women's singles, and helped the team reach the final, settling for a silver medal.

In 2010, she entered the big stage by competing in the Superseries event in Korea Open. In April, she participated at the World Junior Championships in Mexico but had to retire in the quarter-finals due to injury. In June, she experienced the most memorable thing during her career as a badminton player when she reached her first Superseries final on her birthday in Singapore Open. She started in the qualifying draw and went on to reach the final, which she lost to Saina Nehwal in straight games.

In 2011, Tai made good progress by defeating the top-ranked player. She defeated Zhu Lin in the first round of the Australian Open, Wang Xin in the first round of Indonesia Open, and in July, she beat the former world champion Lu Lan in the quarter-finals of the U.S. Open, which was a Grand Prix Gold tournament, and beat World Junior silver medalist Sayaka Sato in the final. This was the first international title she would win, at the age of only 17. She also reached the semi-finals of the Canada, Vietnam, and French Open, where, in France, she defeated China's number 1, Wang Shixian, in the quarter-finals. Tai was awarded best rookie athlete in the 2011 Sports Elite Awards.

In the early half of the 2012 season, her best achievements were the reaching the semi-finals in the All England Open and being ranked as 16th in the world. Tai represented her country as the second women's singles behind Cheng Shao-chieh at the 2012 Summer Olympics in London. The 18-year-old, ranked 13th in the world and seeded 10th won all matches in the group stage defeating Anu Nieminen of Finland and Victoria Montero of Mexico. Her run at the Olympics was stopped by the eventual gold medalist from China Li Xuerui in the round of 16. In September, she claimed her first ever Superseries title in the Japan Open and made history as the youngest player to win a Superseries title (currently the third youngest player, after Ratchanok Intanon, who won the India Open in 2013, and Akane Yamaguchi, who won the Japan Open in 2013). She truly entered the upper echelons and future of the women's game with her victory in Japan and increasingly impressive performances and significant wins over some of the top players. In October, she won the Chinese Taipei Open against Lindaweni Fanetri in a close rubber games 21–19, 20–22, 22–20. In November, she competed as the top-seeded player at the World Junior Championships in Chiba, Japan, but fell in the quarter-finals to Sun Yu. She took part in the World University Championships and won a gold in the women's singles and a silver medal in the women's doubles with her partner Pai Hsiao-ma.

Tai clinched her maiden and only title in 2013 in the Malaysia Open. In other tournaments in the first half of the 2013 season, she often experienced defeat in the quarter-finals, such as in the Germany, Switzerland, Asian Championships, Indonesia, Singapore, as well with her teammate in the Sudirman Cup. Tai then competed in the Summer Universiade and won the silver in the women's singles and bronze in the team event. Her quarter-finals defeat continued into the World Championship. She finally advanced to the final stage in the Chinese Taipei Open but was defeated by Sung Ji-hyun. She next played in the East Asian Games in Tianjin, and won a silver medal in the women's team event. Tai qualified for the Superseries Finals. She defeated Sung Ji-hyun and Porntip Buranaprasertsuk but lost to Wang Shixian in the group stage. She made it to the semi-finals and successfully avenged her loss, beating Wang Shixian. She ended second after losing the final to Li Xuerui.

Tai represented her country at the 2014 Asian Games and won Taiwan's first badminton medal by finishing in third place. She reached her first finals in the Superseries event in the Japan Open but was still unable to defeat the world's number one, Li Xuerui. She then won the Hong Kong Open after beating Nozomi Okuhara in straight games. She extended her winning streak to the Superseries Finals in Dubai and won the first title for Taiwan in the Superseries finals by beating Korea's Sung Ji-hyun in straight games.