A governor (from French gouverneur) is a governing official, usually the executive (at least nominally, to different degrees also politically and administratively) of a non-sovereign level of government, ranking under the head of state. In federations, a governor may be the title of each appointed or elected politician who governs a constituent state.

In countries the heads of the constitutive states, provinces, communities and regions may be titled Governor, although this is less common in parliamentary systems such as in some European nations and many of their former colonies, which use titles such as President of the Regional Council in France and Minister-President in Germany, where in some states there are governorates (German: Regierungsbezirke) as sub-state administrative regions. Other countries using different titles for sub-national units include Spain and Switzerland.

The title also lies, historically, to executive officials acting as representatives of a chartered company which has been granted exercise of sovereignty in a colonial area, such as the British HEIC or the Dutch VOC. These companies operate as a major state within a state with its own armed forces.

There can also be non-political governors: high ranking officials in private or similar governance such as commercial and non-profit management, styled governor(s), who simply govern an institution, such as a corporation or a bank. For example, in the United Kingdom and other Commonwealth countries there are prison governors ("warden" in the United States), school governors and bank governors.

The adjective pertaining to a governor is gubernatorial, from the Latin root gubernare.