William Irwin MLA is a Democratic Unionist Party (DUP) politician in Northern Ireland.
He was elected in 2007 to the Northern Ireland Assembly as a DUP member for Newry and Armagh.
Irwin was the Mayor of Armagh from 2006–07 and serves on Armagh City and District Council.
He is a local dairy farmer.
He entered politics after his son Philip drowned in a swimming pool and he met Ian Paisley.
"He was only 15.
Dr Paisley came and prayed with us and offered great support.