Launceston, also known at some periods as Dunheved, was a parliamentary constituency in Cornwall which returned two Members of Parliament to the British House of Commons from 1295 until 1832, and one member from 1832 until 1918. It was a parliamentary borough until 1885, and a county constituency thereafter.

Launceston is a town, ancient borough, and civil parish in Cornwall, England, United Kingdom. It is 1 mile (1.6 km) west of the middle stage of the River Tamar, which constitutes almost the entire border between Cornwall and Devon. The landscape of the town is generally steep particularly at a sharp south-western knoll topped by Launceston Castle. These gradients fall down to the River Kensey and smaller tributaries.