Aidan Patrick O'Brien is an Irish horse racing trainer. Since 1996, he has been the private trainer at Ballydoyle Stables near Rosegreen in County Tipperary for John Magnier and his Coolmore Stud associates. He is widely acknowledged as one of the greatest horse racing trainers of all time.

The Derby Stakes, also known as the Derby or the Epsom Derby, is a Group 1 flat horse race in England open to three-year-old colts and fillies. It is run at Epsom Downs Racecourse in Surrey on the first Saturday of June each year, over a distance of one mile, four furlongs and 10 yards, or about 1½ miles. It was first run in 1780.