Terence Marne O'Neill, Baron O'Neill of the Maine, PC (NI), was the fourth prime minister of Northern Ireland and leader (1963โ1969) of the Ulster Unionist Party (UUP). A moderate unionist, who sought to reconcile the sectarian divisions in Northern Ireland society, he was a member of the Parliament of Northern Ireland for the Bannside constituency from 1946 until his resignation in January 1970; his successor in the House of Commons of Northern Ireland was Ian Paisley, while control of the UUP also passed to more hard-line elements.