Aidan O'Brien is a renowned Irish horse trainer, known for his success in thoroughbred racing. He is based at Ballydoyle, a training facility in County Tipperary, Ireland. O'Brien has trained numerous champions and has set records in major races, including the Epsom Derby and the Breeders' Cup. O'Brien began his training career in the 1990s and quickly gained recognition for his innovative training methods. He is associated with the Coolmore Stud, one of the largest and most influential breeding operations in the world. His achievements have made him a prominent figure in the horse racing industry.