Ieuan Wyn Jones (born 22 May 1949) is a Welsh politician, and leader of Plaid Cymru's group in the National Assembly for Wales. He was member of Parliament for Ynys Mon, but stood down at the 2001 election in order to spend more time in the Assembly. He was previously president of the party, from 2000, after Dafydd Wigley stood down due to health problems. He resigned in 2003 after a poor showing for the party at Assembly elections.