the most famous throughbred would have to be seabiscut. The most famous horse of all time is Zippo Pine Bar and Zips Choclate Chip. They are both QH and are bred for halter wester & english.
There are several:
Man O War
Secritariat
Seabuscuit
Barbaro
Phar Lap
Ruffian
Right now, more people know about Secritariat because of the new movie but all of these horses were/are famous
Secretariat
ManOWar/War Admiral/Seabiscuit, and others are all famous, too, but Secretariat is tops.
It is cruel to race horses anyway, so I don't think it really matters.
Shergar, as he was stolen and never found.
This years champion is Sea The Stars.
Secretariat most likely. Also, Seabiscuit and Man o' War get much mention.
Most people say Man o' War.
Secretariat
Apparently the most famous breed of horse is the beautiful Arab.
The most famous Quarterhorse halter horse is probably "Impressive"
it is the name of a famous race horse. A movie was made about this horse.
the Clydesdale
secretariat
Secretariat/Red
Thoroughbred horse
Thoroughbreds are one famous breed from England.
Pegasus. the most famous winged horse in mythology
That really depends on where you're from and where you live. In North America, likely the most famous breed of horse would be the American Mustang, followed by the American Quarter Horse. In the Middle East, the most famous breed would be the Arabian horse.
Kentucky
Arion is another kind of horse