Cyllene (1895–1925) was a British Thoroughbred racehorse and sire. In a racing career that lasted from 1897 until 1899, Cyllene won nine of his eleven starts, winning major races and being regarded as the best horse of his generation at two, three and four years of age. In a stud career which began in Britain and ended in Argentina, Cyllene became an important and influential stallion. He sired four winners of The Derby and is the direct male-line ancestor of most modern thoroughbreds.

Bona Vista (1889–1909) was a British Thoroughbred racehorse. As a two-year-old he won the Woodcote Stakes at Epsom Downs. As a three-year-old he won the Newmarket Biennial Stakes, before winning the 2000 Guineas Stakes by one and a half lengths. He was trained by William Jarvis and owned by Charles Day Rose. After retiring from racing Bona Vista became a successful stallion, siring Ascot Gold Cup winner Cyllene. Through his son Cyllene and grandson Polymelus, Bona Vista's sire line is the most dominant in Thoroughbred racehorses today.