Nijinsky (21 February 1967 – 15 April 1992) was a Canadian-bred, Irish-trained champion Thoroughbred racehorse and sire. He was the outstanding two-year-old in Europe in 1969 when he was unbeaten in five races. In the following season, he became the first horse for thirty-five years to win the English Triple Crown, a feat that has not been repeated as of 2022. He is regarded as one of the greatest European flat racehorses of the 20th century.

He was also historically important for establishing the international reputation of his sire Northern Dancer, though Nijinsky was atypical of Northern Dancer progeny in size and conformation. Retired to stud, he became the leading sire in Great Britain & Ireland and the leading broodmare sire in North America. As a winner of top-class races from 6-14 furlongs, Nijinsky is also considered to be among the most versatile of the great horses of the 20th century.