Gentildonna (ジェンティルドンナ, Jentirudonna; 20 February 2009 – 25 November 2025) was a Japanese thoroughbred racehorse and broodmare. In 2012, she won the Japanese Fillies Triple Crown and was voted Japanese Horse of the Year. She was also the first three-year-old filly to win the Japan Cup, in 2012, and the following year became the first two-time winner of that race. In 2014 she added a victory in the Dubai Sheema Classic and finished her racing career by winning the Arima Kinen, earning her a second Horse of the Year award.

Gentildonna was a bay filly bred in Japan by the Northern Farm in Hokkaido. She was sired by the Japanese Triple Crown winner Deep Impact out of the British mare Donna Blini, who won the Group One Cheveley Park Stakes in 2005. Her full sister Donau Blue won the Kyoto Himba Stakes and Sekiya Kinen. The horse's name comes from the Italian word for "noble lady".

Gentildonna began her career by finishing second in a newcomers race but then won a maiden race to finish the season.

Gentildonna began her three-year-old season by winning the Grade 3 Shinzan Kinen against male horses over one mile at Kyoto in January and then finished fourth to Hana's Goal [ja] in the Tulip Sho at Hanshin Racecourse in March.

On 8 April, Gentildonna contested the first leg of the Fillies' Triple Crown, the Oka Sho over one mile at Hanshin. Starting at odds of 3.9/1, she won by half a length from Verxina. Gentildonna and Verxina met again in the Yushun Himba (the Japanese Oaks) on 20 May at Tokyo Racecourse. As Gentildonna's regular jockey Yasunari Iwata was on a 4-day suspension in NHK Mile Cup he was replaced by Yuga Kawada. Verxina was preferred in the betting, but Gentildonna won by five lengths to claim the second leg of the Triple Crown.

After a break of almost four months, Gentildonna returned to contest the Rose Stakes at Hanshin and won by one and a half lengths from Verxina. At Kyoto on 14 October, Gentildonna completed the Triple Crown and defeated Verxina for the fourth time in a row when prevailing by a nose in the Shuka Sho. She was the fourth Japanese Triple Crown winner after Apapane in 2010. On 24 November, Gentildonna faced an international field in the Japan Cup a race which had never been won by a three-year-old filly. Her rivals included the 2011 Japanese Horse of the Year Orfevre and the Prix de l'Arc de Triomphe winner Solemia. Ridden by Yasunari Iwata and despite coming from a very wide barrier draw of 15, Gentildonna won by a nose from Orfevre. There was a protest made for interference by the connections of Orfevre, and Gentildonna had to wait 20 long minutes until her triumph was confirmed, at the cost of subsequent 2-day suspension to Iwata.

On 30 March Gentildonna raced outside Japan for the first time when she started the 11/8 favourite for the Dubai Sheema Classic but was beaten two and a quarter lengths by the Irish six-year-old St Nicholas Abbey. After the race, Yasunari Iwata admitted that St Nicholas Abbey had been the better horse on the night, but pointed out that the filly had been forced to race wide for much of the race. Gentildonna was off the course for almost three months before returning in the Takarazuka Kinen at Hanshin Racecourse. She started the 7/5 favourite, but finished third of the eleven runners behind Gold Ship and the five-year-old Danon Ballade [ja].

Gentildonna began her autumn campaign in the Tennō Shō at Tokyo on 27 October. She started the even money favourite, but finished second, beaten four lengths by the four-year-old colt Just A Way. After three consecutive defeats, Yasunari Iwata lost the ride on Gentildonna, and when the filly appeared to defend the Japan Cup on 24 November, she was ridden by the British jockey Ryan Moore who had received a temporary contract from the JRA. In front of a crowd of 89,719, Gentildonna started the 11/10 favourite ahead of Gold Ship on 2.4/1 and Eishin Flash on 3.9/1. The race was run at a slow pace, and Moore positioned Gentildonna just behind the leaders before accelerating through a gap on the inside to take the lead in the straight. In the closing stages the three-year-old filly Denim And Ruby produced a strong run on the wide outside, but Gentildonna held on to win by a nose, becoming the first horse to win the race twice. Commenting on her earlier run of defeats Ishizaka said "I had been training her to win every time, but I was very relieved that she was able to claim the Cup again in her last start of the season. Thinking about our staff; they've put in so much effort. The fans still believed in her. I was much relieved that she was able to prove she's still a very special horse".