Iwan Gwyn Thomas (born 5 January 1974) is a Welsh sprinter who represented Great Britain and Northern Ireland at the Olympic Games in the 400 metres, and Wales at the Commonwealth Games.
Thomas is a former European, Commonwealth Games and World (4x400m relay) champion.
Thomas is the current UK 400m record holder, having run a time of 44.36s in Birmingham on 13 July 1997.
He was also a member of the team which holds the UK 4x400m Relay record of 2:56.60, set in Atlanta, USA in the Olympic final on 03 August 1996.
Thomas's coach for much of his running career was Mike Smith, formerly coach to British 400 m runners Roger Black, Todd Bennett and Paul Harmsworth also hurdler Kriss Akabusi.
Thomas was made a Member of the Order of the British Empire (MBE) in 1998.