Islwyn (UK Parliament constituency)

Islwyn was a constituency in Wales represented in the House of Commons of the Parliament of the United Kingdom. The area, historically known for coal-mining, had voted for Labour Party candidates since it was created effective at the 1983 general election. Islwyn's first Member of Parliament (MP) was Neil Kinnock, who represented it until he resigned from Parliament in 1995. Kinnock also served as Leader of the Labour Party and Leader of the Opposition from 1983 until 1992.

The constituency was abolished as part of the 2023 Periodic Review of Westminster constituencies and under the June 2023 final recommendations of the Boundary Commission for Wales for the 2024 general election. Its wards were split between Blaenau Gwent and Rhymney, Caerphilly, and Newport West and Islwyn.

Boundaries
1983–2010: The Borough of Islwyn.

2010–2024: The Caerphilly County Borough electoral divisions of Aberbargoed, Abercarn, Argoed, Blackwood, Cefn Fforest, Crosskeys, Crumlin, Maesycwmmer, Newbridge, Pengam, Penmaen, Pontllanfraith, Risca East, Risca West, and Ynysddu.

Elections in the 2010s
Of the 145 rejected ballots:
 * 53 were either unmarked or it was uncertain who the vote was for.
 * 92 voted for more than one candidate.