Apology (1871–1888) was a British Thoroughbred racemare who was the third winner of the Fillies' Triple Crown, winning The Oaks, 1,000 Guineas Stakes and St. Leger Stakes in 1874. Apology was bred and owned by the Reverend John William King, the vicar of Ashby de la Launde, whose ownership of the mare caused a minor scandal in the Church of England after Apology won the St. Leger Stakes. King ultimately had to resign his clerical appointments due to the scandal and died shortly thereafter of a chronic illness. Apology raced until she was five years old, winning the Ascot Gold Cup in 1876. She was retired from racing at the end of 1876 to become a broodmare initially for the widow of John King, and then for Clare Vyner. Apology was euthanised in 1888 after an extended illness.

Apology was bred by the Reverend John William King, who owned her during her racing career. King was the vicar of Ashby de la Launde and had inherited his father Colonel Neville King's Thoroughbred stud and racing stables at the death of his elder brother. Rev. King lived at Ashby Hall in Lincolnshire and raced his horses under the nom de course "Mr. Launde" from 1861 until his death in 1875.

Apology's sire, Adventurer, was a good runner over long distances, winning the City and Suburban Handicap and Ascot Gold Vase as a four-year-old. Adventurer also sired the Classic winners Pretender and Wheel of Fortune. Apology's dam, Mandragora, was bred by W. H. Brook in 1860 and was sired by the Ascot Gold Cup and Doncaster Cup winner Rataplan. Mandragora was the first foal produced by Manganese and was a full sister to the mare Mineral, the dam of the St. Leger winner Wenlock and Derby winner Kisber. Mandragora was a small chestnut mare and was not a successful racehorse at two or three years old. Her racing prowess deemed "not good enough to win a bridle at a fair", she was retired from racing to become a broodmare at Ashgill. Apology was Mandragora's sixth foal and one of four sired by Adventurer. Apology's full sister Agility was a successful racehorse, winning the York Cup twice and the Park Hill Stakes. Another unraced full sister, Analogy, was exported to France and became the dam of the good French long-distance runner Elf. Apology's half-siblings include the good colt Mandrake.

Apology was described by The Times as "a fine looking, powerful chestnut filly, and though a little hollow backed, has very muscular hind quarters, which made her appear somewhat short of work." Her name, "Apology", may have been a tongue in cheek reference to Reverend King's involvement with the turf despite being a member of the clergy, as he did also name his 1875 Derby contender, "Holy Friar".

Apology was trained at Ashgill stables near Middleham in Yorkshire by the Osborne brothers: William, Robert and John. Apology was the third filly, after Formosa and Hannah, to win The Oaks, St. Leger Stakes and 1,000 Guineas Stakes, a series of races now designated as the Fillies Triple Crown.

At Goodwood on 29 July, Apology finished third to Lord Falmouth's colt Atlantic and Mr. Lefevre's colt Regal in the three quarters of a mile Ham Produce Stakes. A few weeks later at Stockton, Apology was beaten by the colt De Cambis in the £260 Lambton Plate. At York, Apology finished second to Mr. Merry's colt Sir William Wallace in the North of England Biennial Stakes. Apology finished second and last to the future Epsom Derby winner George Frederick by half a length in the Municipal Stakes run at Doncaster. In her final start of the year, Apology won the Home-bred Stakes at the Newmarket-Houghton Meeting, beating Lord Falmouth's Blanchefleur and Lord Ailesbury's Aventurière.

On 8 May, Apology ran in the 1,000 Guineas Stakes against a field of nine horses. The race favourites were Apology, La Coureuse, and Lady Bothwell. At the start of the race, the runners broke evenly and continued in a line for the first 200 yards, when La Coureuse took the lead at the Bushes-hill. Apology took the lead on the ascent up the Abingdon Mile Bottom, overtaking the leaders halfway up the hill and winning the race by a margin of three quarters of a length. The second-place finisher La Coureuse and third place horse Blanchefleur were separated by the same distance.

On 17 June, Apology won the Coronation Stakes, beating Blanchefleur. In July at Epsom, Apology won The Oaks against a field of 11 horses. The race was deemed "over" after Apology took the lead at the mile-post, beating Miss Toto and Lady Patricia while running at a canter. In August at the York meeting, Apology finished second by a head to the colt Trent in the Great Yorkshire Handicap after maintaining the lead throughout the race and carrying five extra pounds.