Kilwarlin (1884 – 1900) was a British Thoroughbred racehorse and sire. The detail of his ownership were complicated and led to complaints being lodged with the Jockey Club. He showed considerable promise as a juvenile in 1886 when he won his first two races before being upset at odds of 1/20 in the Bretby Stakes. In the following year he ran unplaced in the Great Jubilee Stakes and then ran three times at Royal Ascot, winning a Biennial Stakes and finishing second in both the Queen's Stand Stakes and the Rous Memorial Stakes (to Ormonde). In autumn he started favourite for the St Leger and won a controversial race despite being left more than 100 yards behind his rivals at the start. After his retirement from racing he became a successful breeding stallion.