Parliamentarian can refer to a member or supporter of a Parliament, as in:
- Member of Parliament
- Roundheads, supporters of the parliamentary cause in the English Civil War
Parliamentarian can also 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 of the National Forensic League, who regulates a chamber of Student Congress