Why, it's something like a horse except that it has two horns, scale armor on its chest and belly, and fangs. Some of them also have a taste for man-flesh. Beautiful creatures they are, but nothing more vicious walks the earth—which may be why Glendar adopted one as the family crest when he took over from Gerridon.
– Marc, God Stalk, "Chapter 8: Voices of the Past"
A rathorn (pronounced rath-orn;) is a carnivorous equine. They can breed with horses, creating half-breeds known as thorns.
Rathorns have an ivory-armored belly, forelegs, chest, neck and head. Both males and females have a short nose horn. Males, in addition, have a second long forehead horn that curves backward and grows throughout the rathorn's life; it will eventually kill them if not constantly filed down.
Most rathorns have black or gray coats, with white manes, tails, and ivory. Pure white ones are albinos.
Jame several times describes rathorns as looking like a cross between dragon and horse.
Rathorns are social creatures, living in herds. A herd of rathorns is called a rage. A rathorn without a rage is known as a death's-head. Because they are social, when Death's-head's mother foresaw his fate, she was saddened by it.
↑ 1.01.1Dark of the Moon, "Chapter 7: A Rage of Rathorns" — "She foresaw that already no rage would ever accept him. He would grow up bitter and alone, a rogue, a death's-head, her child."
↑To Ride a Rathorn, "Chapter I: An Unfortunate Arrival", II — " 'trotting after a crazy rat-horn…' 'That's rath-orn, moron.' "
↑Dark of the Moon, "Chapter 5: Under Green Leaves" — "gouges scarring the stone's side. […] 'Rathorns did that. They must spend about a quarter of their lives hacking at stones like these or at anything hard they can find. Apparently a rathorn's ivory goes on growing throughout its life. It can't do much about the chest and belly plates or the greaves, but unless that big horn is constantly honed down, it eventually curves around so far that it comes through the back of the rathorn's skull. Some scrollsmen even claim that the beast would be immortal if its own armor didn't eventually kill it.' "
↑ 4.04.1The Sea of Time, "Chapter IX: Into the Wastes", I — " 'With those red eyes, he’s an albino, isn’t he?' 'Yes. A rathorn mare’s last foal often is, and an outcast too, poor boy. Others of his kind have black or gray coats, but still white manes, tails, and ivory.' "
↑Dark of the Moon, "Chapter 7: A Rage of Rathorns" — "Jame's first impression was of a black stallion wearing elaborate ivory armor, and then of some fantastic cross between a horse and a dragon. The creature was tall and finely made, with slender legs and a broad chest tapering back to powerful hindquarters. His arched, almost serpentine neck supported a small head encased in an ivory mask, out of which grew the nasal tusk and curved horn of a rathorn stallion. Ivory plates curved around his neck, chest, and abdomen. More ivory sheathed his forelegs like a pair of greaves. His white mane and tail hung against his ebony coat like falls of heavy silk."
↑To Ride a Rathorn, "Chapter XIII: Blood and Ivory"
↑To Ride a Rathorn, "Chapter XVII: Into the Wilds", III — "Captain Hawthorn had called the colt a rogue, a death's-head, adding that no rage would let him join it."
↑Dark of the Moon, "Chapter 5: Under Green Leaves" — " 'only the rathorns move freely there, to mate and to die.' "
↑Dark of the Moon, "Chapter 7: A Rage of Rathorns" — "the sound of rathorn stallions belling in an autumn wood."