The speaker of a deliberative assembly, especially a legislative body, is its presiding officer, or the chair. The title was first used in 1377 in England.

The title was first recorded in 1377 to describe the role of Thomas de Hungerford in the Parliament of England.

The speaker's official role is to moderate debate, make rulings on procedure, announce the results of votes, and the like. The speaker decides who may speak and has the powers to discipline members who break the procedures of the chamber or house. When members speak they address their remarks through the Speaker, and only address them directly whilst referring to other members in the third person. The speaker often also represents the body in person, as the voice of the body in ceremonial and some other situations.

A speaker usually presides the lower house. Different styles are employed to refer to those who preside upper houses or Senates.

By convention, speakers are normally addressed in Parliament as "Mister Speaker" if a man, or "Madam Speaker" if a woman. In other cultures, other styles are used, mainly being equivalents of English "chairman" or "president". Many bodies also have a speaker pro tempore (or deputy speaker), designated to fill in when the speaker is not available.

The speaker is commonly supported by a "speaker's office".

Examples of speakers include:

The president of the National Assembly of Armenia is the speaker of the house in the National Assembly of Armenia. The formation of this position was established on 1 August 1918.