Simon Thomas (born 28 December 1963) is a Welsh Plaid Cymru politician. He was Member of Parliament (MP) for Ceredigion from 2000 to 2005, after winning the seat at a by-election in January 2000 caused by the resignation of Plaid Cymru MP Cynog Dafis. In the 2011 Welsh Assembly election he was elected as member for Mid and West Wales.
He went to Aberdare Boys' Grammar School (became Aberdare Boys' Comprehensive School in 1978) on Cwmdare Road in Trecynon near Aberdare. At the University of College Wales, Aberystwyth, he gained a BA in Welsh in 1985. He gained a Postgraduate diploma from the College of Librarianship Wales (CLW) in Llanbadarn Fawr, Aberystwyth in 1988 (College became part of the university in 1989).
He was assistant curator for the National Library of Wales from 1986-92. From 1992-4, he was Policy and Research Officer for the Taff-Ely borough council. From 1994-2000, he was Rural Development Manager for the JIGSO rural development agency.
Simon Thomas was first elected as MP for Ceredigion in the 2000 by-election following the resignation of Cynog Dafis. He retained the seat for Plaid Cymru at the 2001 election with a reduced majority, and lost it in the 2005 general election to Mark Williams of the Liberal Democrats.
During the 2005 general election Simon Thomas wrote a blog which shows a near daily account of his campaign trail and his thoughts following his defeat.
Simon Thomas lives in Aberystwyth, and had been placed 4th by his party in the National Assembly elections in South Wales Central in 2007, giving him no realistic chance of being elected. However, when the regional lists were published for the Assembly Elections in May 2007, Simon Thomas was notable by his absence in the South Wales Central regional list. The candidates nominated were: 1. Leanne Wood, 2. Chris Franks, 3. Gwenllian Lansdown and 4. Mohammed Sarul Islam.
Following that election, Simon Thomas was appointed a special adviser to the Plaid Cymru ministers in the Welsh Assembly Government coalition between his party and Labour.
The Assembly Election of 2011 saw his political comeback, following his successful nomination for the number 1 spot on the Plaid Cymru regional list for Mid and West Wales in the Welsh Assembly, formerly held by Nerys Evans.
He has announced himself as a candidate for the leadership of Plaid Cymru following the announcement of the resignation of Ieuan Wyn Jones following the 2011 Assembly elections. He withdrew in favour of Elin Jones (running to become her deputy leader instead) on 6 February 2012.
He is married to Gwen, daughter of poet and academic Gareth Alban Davies. They have a son and a daughter.