The Hereford often called the Hereford Hog, is a breed of the domestic pig named for its colour and pattern, which is similar to that of the Hereford breed of cattle: red with a white face. Originating in the United States, the Hereford is a rare variety of swine which was created from a synthesis of Duroc, Poland China, and perhaps some Chester White or Hampshire. It was first developed from 1920 to 1925, and by 1934 the official Hereford registry was opened.

The Hereford was selected for both performance and its unique red-brown and white colouration that resembles Hereford cattle. The breed has always been most popular in the Midwestern United States, especially Illinois, Iowa, and Indiana. The breed grew in numbers into the mid 20th century, but by the 1960s populations plummeted due to a shift in preference by commercial pork operations away from purebred hogs and towards hybrids. Today the American Livestock Breeds Conservancy includes the breed in its watchlist, and estimates about 2,000 breeding animals remain.

Hereford hogs are hardy animals suited for either extensive or intensive production. It has a docile temperament and is suited to use in 4-H and similar programs. It is a medium to large swine breed, and generally weighs 200 to 250 pounds (90 to 110 kg) at five or six months of age. Mature sows weigh about 600 pounds (270 kg) and boars about 800 pounds (360 kg).