Reverend Martin Smyth (born June 15, 1931) is a Northern Ireland unionist politician, and Member of Parliament for South Belfast. He is a member of the Ulster Unionist Party

He used to be Grand Master of the Orange Order, and has been MP for the seat since a 1982 by-election caused by the death of Robert Bradford. He was one of the MPs to resign their seats in 1985 in protest at the Anglo-Irish Agreement. He challenged for the party leadership in 1995 after Jim Molyneaux stood down, but lost to David Trimble.

He is seen as anti-Good Friday Agreement, but not as anti as some, and was in 1993 condemned by the Democratic Unionist Party for suggesting that talks with Sinn Féin might be possible. He challenged David Trimble for the party leadership in 2000, but lost. In 2003 he, along with David Burnside and Jeffrey Donaldson, resigned the party whip. He attempted to dissuade Donaldson from resigning from the party entirely. In January 2004 Smyth and Burnside retook the UUP whip.

In January 2005 he announced he would be stepping down from Parliament at the next election so as to spend more time with his wife.