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.