Lord Lyon (1863–1887) was a British Thoroughbred racehorse that won the 1866 Epsom Derby, 2,000 Guineas Stakes and the St. Leger Stakes, becoming the third winner of the English Triple Crown. Lord Lyon raced until he was four-years old and was retired to stud in 1868. He is considered to be a marginally successful sire with his most notable progeny being the colt Minting and the filly Placida. He was euthanized in April 1887 after several years of failing health.

The 2000 Guineas Stakes is a Group 1 flat race in Great Britain open to three-year-old thoroughbred colts and fillies. It is run on the Rowley Mile at Newmarket over a distance of 1 mile (1.6 km) and scheduled to take place each year at the start of May.