This is a list of by-elections to the Senedd (Welsh Parliament; Welsh: Senedd Cymru; formerly known as the National Assembly for Wales).

Where seats changed political party at the by-election, the result is highlighted.

Assembly term	By-election	Date	Incumbent		Winner		Cause	Retained at next election
2016–2021	Alyn and Deeside	6 February 2018	Carl Sargeant	Labour	Jack Sargeant	Labour	Death (suicide)^[1]	Yes
2011–2016	Ynys Môn	1 August 2013	Ieuan Wyn Jones	Plaid Cymru	Rhun ap Iorwerth	Plaid Cymru	Resignation to lead the Menai Science Park	Yes
2003–2007	Blaenau Gwent	29 June 2006	Peter Law*	Labour	Trish Law	Independent	Death (brain tumour)	Yes
1999–2003	Swansea East	27 September 2001	Val Feld	Labour	Valerie Lloyd	Labour	Death (cancer)	Yes

*Peter Law left the Labour Party and sat as an independent prior to his death. The by-election was won by his widow, but is classed as an independent gain from Labour.

References

^ "Sacked Labour minister Carl Sargeant found dead". BBC News. 7 November 2017. Retrieved 12 July 2021.

v t e By-elections in the United Kingdom
Parliament of the United Kingdom	1801–1806 1806–1818 1818–1832 1832–1847 1847–1857 1857–1868 1868–1885 1885–1900 1900–1918 1918–1931 1931–1950 1950–1979 1979–2010 2010–present Northern Ireland Hereditary peers
Parliament of Great Britain	1707–1715 1715–1734 1734–1754 1754–1774 1774–1790 1790–1800
Parliament of England	1689–1700 1701–1707
Devolved legislatures	Scottish Parliament Senedd (Welsh Parliament)
Other historic	European Parliament (1979–1999) House of Commons of Northern Ireland (1921–72) United Kingdom by-election records
Northern Ireland Assembly vacancies are filled by co-option. Local Government by-election results are generally given on the page for the last election in that area.

See also

References