John Magnier (born 10 February 1948; also known as "The Boss") is an Irish business magnate. He is Ireland's leading thoroughbred stud owner and has extensive business interests outside the horse-breeding industry. Magnier has also been a Senator in the upper house of the Irish Parliament, Seanad Éireann. He is based at Coolmore Stud at Fethard in County Tipperary, considered one of the world's pre-eminent stallion stations, and a nursery of thoroughbreds. Career Origins Magnier was born in Fermoy, County Cork, the eldest son of Thomas Magnier (1909–1962) a County Cork landowner (son of Michael Joseph Magnier of The Manor House, Fermoy, County Cork) by his wife Evelyn Margaret Hallinan (1925–2022), the younger daughter of Major Thomas Francis Dennehy Hallinan of Ashbourne, Glounthaune, County Cork. His aunt Mary Elizabeth Hallinan married Rupert Watson, 3rd Baron Manton, Senior Steward of the Jockey Club 1982–85, effectively the chief executive of the British horse racing industry. Early life Magnier received his formal education at Glenstal Abbey in County Limerick but had to leave school at 15 to take charge of the family estate near Fermoy after his father died. Coolmore Magnier later moved to Fethard, County Tipperary, where he transformed Coolmore Stud into a multi-million-euro international business. The business is headquartered in County Tipperary where a number of other stud farms are part of an extensive network which includes Longfield and Castlehyde studs. The operation also has branches in Versailles, Kentucky and at Jerrys Plains, New South Wales, Australia. Magnier began his association with Coolmore in partnership with his father-in-law and champion racehorse trainer, Vincent O'Brien, and Vernon's Pools magnate, Robert Sangster. They developed the best racing horses and breeding stock, mainly by purchasing the progeny of the great Canadian stallion Northern Dancer. Their forays to the bloodstock auctions at Keeneland Sales furthered their rising stock at home. Eventually, Magnier came to head the operation and thus began an upward spiral of success. His racing empire, which became arguably the most successful on the planet, is nowadays powered by a huge string of blue-blooded thoroughbreds trained at Ballydoyle by Aidan O'Brien, plus dozens of others in the care of a number of other trainers. Champion sires to have stood at Coolmore include the incomparable Sadler's Wells who was leading sire (by prizemoney won) in Great Britain and Ireland in 14 of the 15 years between 1990 and 2004, though his success in his