An English country house is a large house or mansion in the English countryside. Such houses were often owned by individuals who also owned a town house. This allowed them to spend time in the country and in the city—hence, for these people, the term distinguished between town and country. However, the term also encompasses houses that were, and often still are, the full-time residence for the landed gentry who ruled rural Britain until the Reform Act 1832. Frequently, the formal business of the counties was transacted in these country houses, having functional antecedents in manor houses.

With large numbers of indoor and outdoor staff, country houses were important as places of employment for many rural communities. In turn, until the agricultural depressions of the 1870s, the estates, of which country houses were the hub, provided their owners with incomes. However, the late 19th and early 20th centuries were the swansong of the traditional English country house lifestyle. Increased taxation and the effects of World War I led to the demolition of hundreds of houses; those that remained had to adapt to survive.

While a château or a Schloss can be a fortified or unfortified building, a country house, similar to an Ansitz, is usually unfortified. If fortified, it is called a castle, but not all buildings with the name "castle" are fortified (for example Highclere Castle in Hampshire).