Sir Henry Cecil has died at the age of 70 after a long battle with stomach cancer.
Responsible for 25 British Classic winners and crowned champion trainer 10 times, Cecil was also the leading handler by some way at Royal Ascot with a record 75 successes.
Knighted by the Queen in 2011, his later years saw him battle cancer but were illuminated by the great Frankel, officially the best horse in the world and unbeaten in 14 starts before retirement.
A statement posted on his website read: "It is with great sadness that Warren Place Stables confirms the passing of Sir Henry Cecil earlier this morning.
"Following communication with the British Horseracing Authority, a temporary licence will be allocated to Lady Cecil.
"No further update is anticipated this afternoon."
Sir Henry Cecil: a life in pictures
Cecil enjoyed his first British Classic win with Bolkonski in the 1975 renewal of the 2000 Guineas at Newmarket, following up in the same race a year later with Wollow. Both horses were ridden by Frankie Dettori's father, Gianfranco.
Cecil excelled with fillies, and trained six 1000 Guineas winners and eight Oaks victors, with his last Epsom heroine being Light Shift in 2007.
Four Derby winners - Slip Anchor, Reference Point, Commander In Chief and Oath - adorn his record, as do four St Leger triumphs.
However the best was saved until last as Frankel demolished everything put in his path.
He retired to stud with an unbeaten 14-race record and was officially recognised as the greatest horse on the planet.