The Jacob sheep is a rare breed of small, colored with white spots, multi-horned sheep. Jacobs are usually raised for their wool, meat, and hides. They are also kept as pets and ornamental animals, and have been used as guard animals to protect farm property from theft or vandalism and defend other livestock against predators.

Generally referred to as an unimproved or heirloom breed, the Jacob is descended from an ancient Old World breed of sheep, although its exact origins remain unclear. Unlike most other old world breeds, the Jacobs of North America have not undergone extensive cross-breeding and selective breeding; their body resembles that of a goat. Relative to their American counterparts, British Jacobs tend to be larger and heavier, and have lost many of their original characteristics through artificial selection.