What gray horses have won the Grand National?
* Aldaniti * Deteminator * Deep Blue Aldanti wasn't grey! Nicholas Silver was the last grey horse to win the Aintree Grand National.
He won the Aintree Grand National in 2000 and the Irish Grand National in 2000. In 2004 he won the Welsh Grand National. In 2005 he won the Aintree Grand National and the Irish Grand National. So he was won 5 Grand Nationals in total, having won 2 Aintree Grand Nationals, 2 Irish Grand Nationals and 1 Welsh Grand National.
No fillies have won the Grand National but twelve mares have won the race: Miss Mowbray (1852), Anatis (1860), Jealousy (1861), Emblem (1863), Emblematic (1864), Casse Tete (1872), Empress (1880), Zoedone (1883), Frigate (1889), Shannon Lass (1902), Sheila's Cottage (1948) and Nickel Coin (1951). Fillies and mares are both female horses but fillies are aged 4 years or younger.
G. Stevens won the Grand National five times, in 1856, 1863, 1864, 1869 and 1870, and won the Kentucky Derby three times, in 1988, 1995 and 1997. Of course, it isn't the same G. Stevens; the Grand National winner was George Stevens and the Kentucky Derby winner was Gary Stevens. But it's probably the closest to an answer you can get, since no jockey has won both races.