An alderman is a member of a municipal legislative body in a town or city with many jurisdictions. Members of Chicago's city council, for instance, use the title.

The title is derived from the Anglo-Saxon position of Ealdorman, literally meaning "elder-man", and was used by the chief nobles presiding over shires.

In England prior to 1974 municipal or borough councils consisted of councillors and aldermen. Each ward usually elected three councillors for a three-year term, and one alderman to a six-year term. Aldermen tended to have the senior positions within the council only because they were usually the longest serving members, because of party political patronage. Councils can still create honorary aldermen, often a reward for long service. This award is used much more often in Northern Ireland than in England.

In the Corporation of London, aldermen are still elected for each ward, until recently for life. To be a candidate to be Lord Mayor of London, it is necessary to be an alderman and to have been a sheriff.

In the Republic of Ireland the title is used by the first person elected in a multi-seat local government ward.