Troy (25 March 1976 – 12 May 1983) was an Irish-bred, British-trained Thoroughbred racehorse and sire. In a career that lasted from 1978 to 1979, he ran eleven times and won eight races. He is most notable for his form in the summer of 1979, when he won the 200th running of the Derby and subsequently added victories in the Irish Derby, the King George VI and Queen Elizabeth Stakes and the Benson and Hedges Gold Cup. He was retired to stud at the end of the season. His career as a stallion lasted only four years before he died in 1983.

Troy, a big, powerfully built bay horse with three white socks, was bred in County Meath, Ireland, by the Ballymacoll Stud, the breeding operation of his owners, industrialist Sir Michael Sobell and his son-in-law Lord Weinstock. He was sired by Petingo, the leading English two-year-old of 1967, and was out of the mare La Milo. La Milo had previously produced Washington D. C. International winner Admetus. Troy was sent into training with Dick Hern at West Ilsley in Berkshire.

Troy made his racecourse debut in summer of 1978, wearing the light blue silks of his owners, when he finished second in a six furlong maiden race. In his next start, he moved up in distance for the Plantation Maiden Stakes over seven furlongs at Newmarket Racecourse in June and won by two lengths from Warmington. He was then moved up in class for the Listed Vintage Stakes at Goodwood Racecourse in July. Starting at odds of 2/1 he was restrained by Carson at the rear of the six-runner field before taking the lead in the final furlong and winning by two and a half lengths from Ela-Mana-Mou.

Troy was again moved up in class and distance for his final start of the year in the Group Two Royal Lodge Stakes, over one mile at Ascot Racecourse in September. He chased the leader Lyphard's Wish before taking the lead a furlong from the finish but was overtaken in the closing stages and was beaten three quarters of a length by Ela-Mana-Mou.

In the spring of 1979, Troy was prepared for the Epsom Derby by running in two of the recognised trial races. In early May, he ran in the Classic Trial Stakes over ten furlongs at Sandown. He started the 4/7 favourite but looked less than fully fit and was not particularly impressive as he "scrambled" home to win by a neck from Two of Diamonds. The form was made to look somewhat better when Two of Diamonds won the Dee Stakes at Chester Racecourse. Later in the month, he was moved up in distance for the mile and a half Predominate Stakes at Goodwood. He took the lead approaching the final furlong and drew right away from his opponents without being put under any pressure and won by seven lengths Serge Lifar and Galaxy Libra. At the time it was felt that, while he had won the race impressively, he had beaten mediocre opposition, but Serge Lifar went on to win the Scottish Derby, whilst Galaxy Libra became a leading turf performer in the United States, winning the Sunset Handicap and the Man o' War Stakes in 1981.

In the 200th Derby on 6 June, Troy started third favourite behind Milford and Ela-Mana-Mou at odds of 6/1 in a field of twenty-three runners. Milford, also trained by Hern, was owned by the Queen and was popular with the public, but had been passed over by stable jockey Willie Carson in favour of Troy. Carson held Troy up in the early stages and entered the straight in thirteenth place behind the front-running Lyphard's Wish. Carson moved Troy to the outside, where he produced a strong run to take the lead a furlong and a half from the finish. In the closing stages, he drew away to win by seven lengths from Dickens Hill with Northern Baby in third ahead of Ela-Mana-Mou. The unplaced horses included Cracaval, Niniski, Son of Love and Tap On Wood. The form of the race was particularly strong: Dickens Hill won the Eclipse Stakes in July; Cracaval upset Ile de Bourbon in the September Stakes and Northern Baby won the Champion Stakes in October. Michael Sobell called the result "the culmination of twenty years of ownership", while Carson described Troy as "the best colt I have ever ridden."

At the end of the June, Troy contested the Irish Derby at the Curragh in which he was reopposed by Dickens Hill, with the other runners including the French challengers Scorpio and the undefeated Fabulous Dancer. After turning into the straight in fifth place behind the Irish-trained outsider The Bart he took the lead approaching the final furlong and won by four lengths from Dickens Hill, Bohemian Grove, Scorpio and The Bart. In July, Troy raced against older horses for the first time in the King George VI and Queen Elizabeth Stakes at Ascot. His task was made easier by the absence of Ile de Bourbon, the 1978 winner, who was withdrawn after contracting a "virus". He started at odds of 2/5 with his main opposition looking likely to come from the French four-year-old Gay Mecene. Troy raced in fourth place before moving up to overtake Ela-Mana-Mou in the straight and held the late challenge of Gay Mecene to win by 1+1⁄2 lengths, with Ela-Mana-Mou holding on to take third ahead of M-Lolshan. He became the fourth horse after Nijinsky, Grundy and The Minstrel to complete the Derby-Irish Derby-King George treble. His performance was described as "workmanlike" and "unspectacular" with Timeform commenting that he was almost certainly unsuited by the relatively slow early pace. At York in August, Troy was brought back in distance for the Benson and Hedges Gold Cup over 10+1⁄2 furlongs and started the 1/2 favourite. He appeared outpaced in the early stages and was ten lengths behind the leaders Lyphard's Wish and Crimson Beau with three furlongs left to run. He produced a sustained run in the straight to take the lead inside the final furlong and was eased down in the final strides to win by three quarters of a length from Crimson Beau.

Troy's final race was the Prix de l'Arc de Triomphe at Longchamp Racecourse on 7 October. He started the 4/5 favourite in a field of twenty-two runners which included Top Ville, Le Marmot, Three Troikas, Fabulous Dancer, Ile de Bourbon, Trillion, Crimson Beau, Two of Diamonds and Northern Baby. He was not far behind the leaders on the final turn, but his usual finishing run failed to materialse, and although he made some progress in the closing stages and finished third behind Three Troikas and Le Marmot. Timeform commented that Troy had failed to reproduce his best form, speculating that he had not recovered from his hard race at York.