Niniski (15 February 1976 – November 1998) was an American-bred, British-trained Thoroughbred racehorse and sire. In a racing career which lasted from October 1978 until October 1980, he ran fourteen times and won six races. After showing some promise in his early races he emerged as a top-class stayer in the autumn on 1979, winning the Geoffrey Freer Stakes, Irish St Leger and Prix Royal-Oak.