President: Ulysses S. Grant
During the Civil War, Grant rode a large horse by the name of Jeff Davis and another called Cincinnatus that was given to him by an admirer after the Battle of Chattanooga. He didn't let anyone other than President Lincoln ride Cincinnatus once it was in his possession. He also rescued a horse that had been abandoned by the confederates on the battlefield, after recognizing that he was a thoroughbred and named him "Kangaroo." Kangaroo was severely underweight when Grant took him in, but was quickly rehabilitated.
During his presidency, he was twice overtaken in one day by a horse that was pulling a butcher's delivery cart. Try as he might on a horse about which we know nothing, he could not catch this delivery horse. The next day, he found the butcher's shop and bought the horse, which he named "Butcher Boy."
Grant also owned a few race horses, the most famous of which were Julia and Nellie.