In 2004, when the Senate agreed to designate December 13 as the National Day of the Horse, the resolution acknowledged that "horses continue to permeate the society of the United States, as witnessed on movie screens, on open land, and in our own backyards" and are "a vital part of the collective experience of the United States."
Nowhere is that vital role clearer than in the archive of LIFE Magazine's great 20th century photography, which features these majestic creatures in all of their many roles. They're athletes (Seabiscuit), movie stars (National Velvet), military troops, farm workers, even gamblers — not to mention beloved companions. In one 1952 gimmick, a horse that supposedly possessed clairvoyant powers even composed a headline for a LIFE story about herself. (She was clairvoyant, not creative: the headline was "Talking Horse.")
To mark the celebration of horses now and then, here's a look back at 25 of the most memorable horses in LIFE's pages.