Parliamentarian has two principal meanings.
First, it may refer to a member or supporter of a Parliament, as in:
- Member of parliament
- Roundhead, supporter of the parliamentary cause in the English Civil War
Second, in countries that do not refer to their legislative bodies as a parliament, parliamentarian may instead refer to an expert adviser on parliamentary procedure, as in:
- Parliamentarian (consultant), an officer or outside consultant designated by an organization to serve as an expert in parliamentary procedure
- Parliamentarian of the United States House of Representatives
- Parliamentarian of the United States Senate
- A member of the National Association of Parliamentarians
- A member of the American Institute of Parliamentarians
- An official in Congressional Debate, a scholastic debate format