Lord mayor is a title of a mayor of what is usually a major city in a Commonwealth realm, with special recognition bestowed by the sovereign. However, the title or an equivalent is present in other countries, including forms such as "high mayor". Aldermen usually elect the lord mayor from their ranks.

In many countries, a mayor is the highest-ranking official in a municipal government such as that of a city or a town. Worldwide, there is a wide variance in local laws and customs regarding the powers and responsibilities of a mayor as well as the means by which a mayor is elected or otherwise mandated. Depending on the system chosen, a mayor may be the chief executive officer of the municipal government, may simply chair a multi-member governing body with little or no independent power, or may play a solely ceremonial role. A mayor's duties and responsibilities may be to appoint and oversee municipal managers and employees, provide basic governmental services to constituents, and execute the laws and ordinances passed by a municipal governing body. Options for selection of a mayor include direct election by the public, or selection by an elected governing council or board.