Darley Arabian
Each of the three major foundation sires was, coincidentally, the ancestor of a grandson or great-great-grandson who was the only male descendant to perpetuate each respective horse's male line: Matchem was the only descendant of his grandsire, the Godolphin Arabian, to maintain a male line to the present; the Byerley Turk's male line was preserved by Herod (or King Herod), a great-great-grandson; and the male line of the Darley Arabian owes its existence to great-great-grandson Eclipse, who was the dominant racehorse of his day and never defeated. One genetic study indicates that 95% of all male Thoroughbreds trace their direct male line (via the Y chromosome) to the Darley Arabian.