I will assume by "derby" you mean Kentucky Derby. I will also assume that you only mean winners of the Derby. There have been two Derby-winning horses with 15 letters in their names: Foolish Pleasure (1975) and Fusaichi Pegasus (2000).
Thoroughbred horses compete in the Kentucky Derby.
All were colts in the 2011 Kentucky Derby. With the exception of one gelding, Comma To The Top
The Kentucky Derby
In terms of horses, the 2009 Kentucky Derby winner was Mine That Bird. In terms of people, the winning jockey was Calvin Borel. The winning trainer was Bennie L. Woodley, Jr. And the winning owner was an outfit called Double Eagle Ranch.
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there are horse races in kentucky - kentucky derby
The Kentucky Derby didn't begin until 1875.
For horses, the Derby in America, known as the Kentucky Derby, is run in Louisville, Kentucky, on the first Saturday in May every year.
Jockey Kent Desormeaux rode 'Real Quiet' to win the 1998 Kentucky Derby.