The October Horse is the sixth novel in Colleen McCullough's Masters of Rome series.

[1] It was first published in November 2002 by Century in UK and Simon & Schuster in USA.

The book begins with Gaius Julius Caesar's Egyptian campaign in Alexandria, his final battles with the Republicans led by Metellus Scipio, Cato the Younger, Titus Labienus and the brothers Pompeius in Africa and Spain, and ultimately Caesar's assassination on the Ides of March by Marcus Brutus, Gaius Cassius and the Liberators.

The title of the book comes from a peculiar chariot race in Rome on the Ides of October, after which the right-hand horse of the winning team was sacrificed to the Roman gods.

Kirkus Reviews says the book is "a rousing and richly satisfying take on some of history's real beings.