The Cavalier King Charles Spaniel is a toy dog breed from the United Kingdom. Blenheim (chestnut and white), tricolor (black/white/tan), black and tan, and ruby are the four recognized colors; the coat is smooth and silky. The average lifespan is between eight and twelve years.

When the Cavalier King Charles was interbred with flat-nosed breeds in the late seventeenth century, it changed dramatically. It had the same history as the smaller King Charles Spaniel until the 1920s. Breeders attempted to recreate what they thought was the original configuration - a dog resembling Charles II's spaniel from the English Civil War, when supporters of the king were referred to as Cavaliers.