| Name | Color | Sex | Year of birth | Microchip | Sire | Dam | Breed | Breeder |
|---|---|---|---|---|---|---|---|---|
| William The Third | bay | c | 1898 | St. Simon | Gravity | Thoroughbred | Great Britain | |
| William's Pride | bay | f | 1911 | William The Third | Stop Her | Thoroughbred | Great Britain | |
| Williams Forester | chestnut | c | 1750 | Crofts Forester | Looby Mare | Thoroughbred | Great Britain | |
| Williams High | grey | c | 2015 | 643093300024832 | 0827-5 Highest Lover | 4561-6 Woody Land | Thoroughbred | Mr Botashev D.Kh. |
| Williams Woodstock Arabian | grey | c | Thoroughbred | |||||
| Williamstone | d.-bay | c | 1990 | Seattle Slew | Winter Sparkle | Thoroughbred | USA | |
| Willing Maid | chestnut | f | 1972 | Olden Times | Lady o'War | Thoroughbred | USA | |
| Willnt | bay | f | 1978 | Nostrum | Chateaurullah | Thoroughbred | USA | |
| Willonyx | br. | c | 1907 | William The Third | Tribonyx | Thoroughbred | Great Britain | |
| Willow Ann | chestnut | f | 1942 | Solario | Court of Appeal | Thoroughbred | Great Britain |