Aidan O’Brien

Aiden O'Brien
Credit: Aidan O’Brien

Aidan Patrick O’Brien was born in County Wexford, Ireland, on the 16th of October 1969. There is certainly an argument that, if not for the existence of Willie Mullins, Aidan O’Brien would be considered to be the best horse racing trainer of all time.

He was one of six children of Denis and Stella O’Brien, with Dennis being a farmer and small-scale racehorse trainer, which is where Aidan got the bug from. Aidan O’Brien and his wife, Anne-Marie, have four children, with all of Joseph, Sarah, Anastasia and Donnacha following their father’s footsteps by becoming jockeys, although not yet as successful trainers.


When Aidan O’Brien began working with horses in a professional environment it was at the racing stables of P.J. Finn’s in Curragh, County Kildare. He then went on to work with Jim Bolger at Coolcullen in County Carlow. He married Anne-Marie Crowley whose father, Joe Crowley was training horse at Piltown, County Kilkenny. Aidan O’Brien took over the running of the yard in 1993, but in 1996 he moved to the Ballydoyle yard of John Magnier after he was approached to do so. For a time, he ran both yards alongside each other before moving to effectively run Ballydoyle on his own, making it a roaring success.

He enjoyed his first Group success when Desert King won the National Stakes to hand him his first Group 1 victory, then the same horse followed that up with the Irish 2,000 Guineas a year later. When it comes to flat racing there is barely a race that hasn’t been won by a horse that Aidan O’Brien has trained. It helps, of course, that he’s backed by the Coolmore operation, which spends huge sums of money every year in the and elsewhere. Even so, he is one of the most successful trainers ever, winning races across the United Kingdom, Ireland, the United Arab Emirates and the United States of America, to name just a few of the countries he’s trained winners in.

Major Successes

When you are considered to be one of the most successful trainers of all time, it goes without saying that you know how to win big races. He is, at the time of writing, the most successful trainer ever in the Epsom Derby, for example. Here are just a few of those that Aidan O’Brien has won during his career:

  • 1,000 Guineas
  • 2,000 Guineas
  • Epsom Derby
  • St Leger
  • King George VI & Queen Victoria Stakes
  • Triumph Hurdle
  • UAE Derby
  • Breeders’ Cup Turf
  • Prix de l’Arc de Triomphe
  • Irish Champion Stakes

Horses Trained

Given Aidan O’Brien’s success over the years, it is hardly a surprise that he has worked with some of the greatest horses ever to take part in flat racing events. In many ways, it is impossible to pick out a selection of horses to talk about in relation to him, with horses from Capri to Yeats, George Washington to Spartacus all coming under his tutorship. Here are some of the big names that were trained by Aidan O’Brien:


In spite of the fact that Aidan O’Brien is one of the best flat racing trainers of all time, Istabraq is actually best-known for his success over jumps. He began life as a flat racing horse, but it was decided that he would run over jumps and he made his hurling debut in 1996. He actually lost in his first race over hurdles, but that simply told the lie of how successful he would go on to become. He won the Champion Hurdle three times, managing it for the first time in 1998 before following that up over the next two years in succession. His list of wins also includes the likes of the Hatton’s Grace Hurdle, the Aintree Hurdle and the Punchestown Champion Hurdle.

Desert King

The first winner of a Group 1 race for Aidan O’Brien was Desert King, who started 12 races and won five of them for a very respectable return. He also placed five times in the other races, with his notable wins being the National Stakes and Tetrach Stakes before winning in the Irish 2,000 Guineas and the Irish Derby, both in 1997. A year later and Desert King was put out to stud, heading to the Coolmore Stud in Ireland. He was the Champion three-year-old of his year, with the horses that are considered to be his progeny including Maybe Diva, Chelsea Rose and Desert War. He died on the 11th of August 2021.

Dylan Thomas

The racing career of Dylan Thomas lasted from June 2005 until December 2007, during which he won some huge races for his trainer Aiden O’Brien. In 2006 he was considered to be one of the best three-year-olds in Europe, winning the Derrinstown Stud Derby Trial, the Irish Derby and the Irish Champion Stakes, but it was a year later that his performances went up another level. That was when he won two of the biggest races on the flat, enjoying success in the King George VI & Queen Victoria Stakes and the Prix de l’Arc de Triomphe. That saw him crowned the European Horse of the Year for 2007 as well as the European Champion Older Horse.

Auguste Rodin

Foaled on the 26th of January, 2020, Auguste Rodin is a well-bred horse and was considered to be the best juvenile of his generation across Europe in 2022. That was in no small part due to the fact that he won three of the four races that he took part in, which included to Vertem Futurity Trophy. It was the following year that helped him make it onto this list, though, when he won the Epsom Derby, a record ninth win as trainer for Aidan O’Brien, as well as the Irish Derby, the Irish Champion Stakes and the Breeders’ Turf Cup in the United States of America.