A government or state agency, often an appointed commission, is a permanent or semi-permanent organization in the machinery of government that is responsible for the oversight and administration of specific functions, such as an intelligence agency. There is a notable variety of agency types. Although usage differs, a government agency is normally distinct both from a department or ministry, and other types of public body established by government. The functions of an agency are normally executive in character, since different types of organizations (such as commissions) are most often constituted in an advisory role—this distinction is often blurred in practice however.

A government agency may be established by either a national government or a state government within a federal system. The term is not normally used for an organization created by the powers of a local government body. Agencies can be established by legislation or by executive powers. The autonomy, independence and accountability of government agencies also vary widely.