Secretariat (March 30, 1970 – October 4, 1989) was an American Thoroughbred racehorse who, in 1973, became the first Triple Crown winner in 25 years. His record-breaking victory in the Belmont Stakes, which he won by 31 lengths, is widely regarded as one of the greatest races of all time. During his racing career, he won five Eclipse Awards, including Horse of the Year honors at ages two and three. He was nominated to the National Museum of Racing and Hall of Fame in 1974. In the List of the Top 100 U.S. Racehorses of the 20th Century, Secretariat is second only to Man o' War (racing career 1919–1920), who also was a large chestnut colt given the nickname "Big Red".

Possibly the most well-known horse on this list is the legendary race horse, Seabiscuit. Seabiscuit’s story is remembered because he overcame adversity to become one of the best racehorses of all time. Seabiscuit was smaller in stature than most and initially he was not a very good racehorse as he failed to win his first 17 races. It wasn’t until he was paired with jockey Red Pollard that his racing luck began to turn around. Seabiscuit started winning race after race and soon he was a favorite in California. Pollard became injured but Seabiscuit kept on winning and beat War Admiral in an amazing match race, but was injured in a race afterward. Seabiscuit and Pollard, who were both expected to have injuries that kept them from racing again, recovered together and continued to beat the odds and win races together again.

Man o' War (March 29, 1917 – November 1, 1947) was an American Thoroughbred who is widely considered one of the greatest racehorses of all time. Several sports publications, including The Blood-Horse, Sports Illustrated, ESPN, and the (AP) Associated Press, voted Man o' War as the outstanding horse of the 20th century. During his racing career just after World War I, Man o' War won 20 of 21 races and $249,465 (equivalent to $3,120,000 in 2018) in purses. He was the unofficial 1920 American horse of the year and was honored with Babe Ruth as the outstanding athlete of the year by The New York Times. He was inducted into the National Museum of Racing and Hall of Fame in 1957. On March 29, 2017, the museum opened a special exhibit in his honor, "Man o' War at 100".