Roderick O'Connor (1910 – 23 January 2000) was a nationalist politician in Northern Ireland.
O'Connor was a solicitor and a director of the Ulster Herald series of newspapers. He became active in the Nationalist Party and sat on various boards in County Tyrone. 
O'Connor was elected at the 1949 Northern Ireland general election for West Tyrone, and held his seat at each subsequent election, until the Parliament of Northern Ireland was abolished in 1972.  In 1958, he worked with Eddie McAteer to prevent the Nationalist Party becoming the official opposition at Stormont. When, in 1965, they finally accepted the role, O'Connor became the Opposition Chief Whip and the Shadow Minister of Home Affairs. In 1969, he became the final Chairman of the Nationalist Party at Stormont. 
The Parliament of Northern Ireland was the home rule legislature of Northern Ireland, created under the Government of Ireland Act 1920, which sat from 7 June 1921 to 30 March 1972, when it was suspended because of its inability to restore order during The Troubles, resulting in the introduction of Direct Rule. It was abolished under the Northern Ireland Constitution Act 1973.
Joseph Austin Currie was an Irish politician who served as a Minister of State for Justice with responsibility for Children's Rights from 1994 to 1997. He served as a Teachta Dála (TD) for the Dublin West constituency from 1989 to 2002, representing Fine Gael, and as a Member of the Parliament of Northern Ireland (MP) for East Tyrone from 1964 to 1972, representing the Nationalist Party and later the Social Democratic and Labour Party (SDLP).
Terence Marne O'Neill, Baron O'Neill of the Maine, PC (NI), was the fourth prime minister of Northern Ireland and leader (1963–1969) 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.
The House of Commons of Northern Ireland was the lower house of the Parliament of Northern Ireland created under the Government of Ireland Act 1920. The upper house in the bicameral parliament was called the Senate. It was abolished with the passing of the Northern Ireland Constitution Act 1973.
William "Bill" Craig was a Northern Irish politician best known for forming the Unionist Vanguard movement.
Henry William West was a politician in Northern Ireland who served as leader of the Ulster Unionist Party from 1974 until 1979.
Abstentionism is standing for election to a deliberative assembly while refusing to take up any seats won or otherwise participate in the assembly's business. Abstentionism differs from an election boycott in that abstentionists participate in the election itself. Abstentionism has been used by Irish republican political movements in the United Kingdom and Ireland since the early 19th century. It was also used by Hungarian and Czech nationalists in the Austrian Imperial Council in the 1860s.
Eddie McAteer was an Irish nationalist politician in Northern Ireland.
Michelle O'Neill is an Irish politician who served as deputy First Minister of Northern Ireland between 2020 and 2022. She has been serving as Vice President of Sinn Féin since 2018 and is the Member of the Legislative Assembly (MLA) for Mid Ulster since 2007.
Thomas James Stanislaus Harbison was an Irish nationalist politician.
Joseph Francis Stewart was an Irish nationalist politician.
The Nationalist Party was the continuation of the Irish Parliamentary Party (IPP), and was formed after the partition of Ireland, by the Northern Ireland-based members of the IPP.
Thomas Joseph Campbell, known as T. J. Campbell, was an Irish politician, barrister, journalist, author and judge.
South Tyrone was a constituency of the Parliament of Northern Ireland.
John Carron (1909–1998) was a nationalist politician in Northern Ireland.
West Tyrone was a constituency of the Parliament of Northern Ireland.
In Northern Ireland, the Leader of the Opposition was the leader of the largest political party in the House of Commons of Northern Ireland that was not in the government of the day. The position was eliminated in 1972 when the Stormont Parliament was abolished and replaced by direct rule from London.
The 2022 Northern Ireland Assembly election was held on 5 May 2022. It elected 90 members to the Northern Ireland Assembly. It was the seventh assembly election since the establishment of the assembly in 1998. The election was held three months after the Northern Ireland Executive collapsed due to the resignation of the First Minister, Paul Givan (DUP), in protest against the Northern Ireland Protocol.
Matthew John O'Toole MLA is an Irish Social Democratic and Labour Party (SDLP) politician, former civil servant, and journalist who has served as a Member of the Legislative Assembly (MLA) for the Belfast South constituency in the Northern Ireland Assembly since January 2020. He is the current Leader of the Opposition in the Northern Ireland Assembly.