Born in Killegney Townland, County Wexford on October 16, 1969, Aidan O’Brien has been described by the ‘Racing Post’ as “the world’s most powerful trainer”. O’Brien saddled his first winner, Wandering Thoughts, ridden by Pat Gilson, in a seven-furlong handicap at Tralee on June 7, 1993. He went on to become Irish Champion National Hunt Trainer five years running between 1993/94 and 1997/98 and famously saddled Istabraq to a hat-trick in the Champion Hurdle at the Cheltenham Festival in 1998, 1999 and 2000.
By that stage of his career, O’Brien had been recruited as private trainer to John Magnier and his Coolmore Stud associates, Michael Tabor and Derrick Smith, at Ballydoyle, near Rosegreen, County Tipperary. O’Brien became Irish Champion Flat Trainer for the first time in 1999 and has retained his title ever since. In 2001, he became the British Champion Flat Trainer for the first time, making him the first overseas winner since his unrelated namesake, and the previous master of Ballydoyle, Vincent O’Brien in 1977. O’Brien retained his title in 2002 and won it again in 2007, 2008, 2016, 2017, 2024 and 2025.
On British soil, O’Brien has won the Derby a record 12 times, most recently with Christmas Day in 2026, the Oaks 11 times, the 2,000 Guineas a record 10 times, the St. Leger nine times and the 1,000 Guineas eight times. In his native land, his record is no less impressive, with a 17 wins in the Irish Derby, 13 in the Irish 2,000 Guineas,12 in the Irish 1,000 Guineas, eight in the Irish Oaks and seven in the Irish St, Leger. O’Brien is, in fact, the most successful trainer in the history of all the Irish Classics bar the Irish St. Leger. Beyond Great Britain and Ireland, O’Brien has won the Breeders’ Cup Turf eight times and the Prix de l’Arc de Triomphe twice, among countless other intermational successes.
