Which was the most successful thoroughbred stallion of all time?

Which was the most successful thoroughbred stallion of all time?  At the time of his death, at the age of 23, in July, 2021, Galileo had sired 91 individual Group 1 winners and been crowned leading sire in Great Britain and Ireland every year, bar one, since 2008. Bred and owned by John Magnier and his Coolmote associate Michael Tabor, won the Derby, Irish Derby and King George VI and Queen Elizabeth Stakes during his three-year-old campaign, in 2001, and was named Cartier Champion Three-year-old Colt.

However, it was as a sire and, indeed, as a sire of sires – 20 of his progeny went on to sire Group 1 winners – that Galileo would make his name. Sired by Sadler’s Wells, from the family of Northern Dancer, out of Urban Sea, who won the Prix de l’Arc de Triomphe in 1993, Galileo was described by John Magnier as ‘a very special horse’.

Of course, Galileo was the first Derby winner to be trained at Ballydoyle, Co. Tipperary since the days of Vincent O’Brien, but his progeny also included five Derby winners. They were, in chronological order, New Approach in 2008, Ruler Of The World in 2013, Australia in 2014, Anthony Van Dyck in 2019 and Serpentine in 2020. The crème de la crème of his offspring, though, was Frankel, unbeaten in 14 races, including ten at Group 1 level, and the highest rated horse of all time, according to World Thoroughbred Rankings.