A postmaster is the head of an individual post office, responsible for all postal activities in a specific post office. When a postmaster is responsible for an entire mail distribution organization (usually sponsored by a national government), the title of Postmaster General is commonly used. Responsibilities of a postmaster typically include management of a centralized mail distribution facility, establishment of letter carrier routes, supervision of letter carriers and clerks, and enforcement of the organization's rules and procedures. The postmaster is the representative of the Postmaster General in that post office.

In Canada, many early places are named after the first postmaster.