The Guernsey is a breed of dairy cattle from the island of Guernsey in the Channel Islands. It is fawn or red and white in colour, and is hardy and docile. Its milk is rich in flavour, high in fat and protein, and has a golden-yellow tinge due to its high β-carotene content. The Guernsey is one of three Channel Island cattle breeds; the other two are the Alderney, which is now extinct, and the Jersey.

Dairy cattle are cattle bred with the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species Bos taurus.