Breconshire or Brecknockshire was a constituency in Wales which returned one Member of Parliament (MP) to the House of Commons of the English Parliament, and later to the Parliament of Great Britain and of the United Kingdom, between 1542 and 1918.

Until 1974, Brecknockshire, also formerly known as the County of Brecknock, Breconshire, or the County of Brecon, was an administrative county in the south of Wales, later classed as one of the thirteen historic counties of Wales. Named after its county town of Brecon, the county was mountainous and primarily rural.