Ivan Foster (born 1943) is a retired senior minister in the Free Presbyterian Church of Ulster and a former Democratic Unionist Party politician.
 He is a lifelong friend and associate of the Democratic Unionist politician and Free Presbyterian Church leader Ian Paisley.
 But in November 2006, he became the most prominent Free Presbyterian to openly challenge Ian Paisley's decision to enter into a power-sharing government with Sinn Féin and went on to denounce Ian Paisley from the pulpit of his church in January 2007.
Noel Doherty (26 December 1940 – 26 December 2008) was a Northern Irish loyalist activist who was close to Ian Paisley during Paisley's early years in politics.
 He served as leader of the Ulster Protestant Volunteers and was imprisoned for his involvement in procuring explosives for that organisation.
Ian Richard Kyle Paisley Jr (born 12 December 1966) is the Member of Parliament (MP) for North Antrim, in office since 2010.
 Previously he was a member of the Northern Ireland Assembly for North Antrim from 1998 to 2010.
 Paisley, who is a member of the Democratic Unionist Party (DUP), is the son of the DUP's founder, Ian Paisley.
Terence Marne O'Neill, Baron O'Neill of the Maine, PC (10 September 1914 – 12 June 1990) 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 Member of the Parliament of Northern Ireland for the Bannside constituency from 1946 until his forced resignation in April 1969 as communal conflict erupted; his successor in Parliament was Ian Paisley, while control of the UUP also passed to more hard-line elements.
John Thomas Atkinson Glass (8 September 1936 – 24 February 2004), often known as Pastor Jack Glass or simply as Jack Glass, was a Scottish Protestant preacher, evangelicalist and political activist.
 Pastor Glass is most readily associated with his strong views on unionism in Northern Ireland, his anti-Catholic speeches and his association with his friend and colleague the Rev. Ian Paisley.
 According to his obituary in "The Times", Glass was seen as Scotland's answer to Ian Paisley.
Rhonda Paisley (born 1960) is an author, and former politician from Northern Ireland.
 She is the second daughter of the late Democratic Unionist Party (DUP) leader and Northern Ireland's former First Minister Ian Paisley, is unmarried, and lives with her mother in the family home.
 She attended Bob Jones University in the United States (the same institution from which her father received his honorary degree), where she was awarded a BA in Fine Art.
Eileen Emily Paisley, Lady Bannside, Baroness Paisley of St George's ("née" Cassells; born 2 November 1931, Belfast), is a Northern Irish Unionist politician, a vice-president of the Democratic Unionist Party, and the widow of Ian Paisley, Lord Bannside, former leader of the DUP.
 She became a life peer in 2006.
Ian Richard Kyle Paisley, Baron Bannside, PC (6 April 1926 – 12 September 2014) was a loyalist politician and Protestant religious leader from Northern Ireland.
Baron Rathcavan, of The Braid in the County of Antrim, is a title in the Peerage of the United Kingdom.
 It was created in 1953 for the Unionist politician Sir Hugh O'Neill, 1st Baronet.
 He had already been created a Baronet, of Cleggan in the County of Antrim, in 1929.
 O'Neill was the third son of Edward O'Neill, 2nd Baron O'Neill (see the Baron O'Neill for earlier history of the family) and the uncle of the Prime Minister of Northern Ireland Terence O'Neill, Baron O'Neill of the Maine.
 Lord Rathcavan was also a male-line descendant of Edward Chichester, 1st Viscount Chichester (see the Marquess of Donegall).
 He was succeeded by his eldest surviving son, the second Baron.
 He succeeded his father as Unionist Member of Parliament for Antrim in 1952, a seat he held until 1959, and was later a member of the Parliament of Northern Ireland.
 s of 2014 the titles are held by his son, the third Baron, who succeeded in 1994.
 As a descendant of both the second Baron O'Neill and the first Viscount Chichester, Lord Rathcavan is in remainder to the barony of O'Neill as well as to the viscountcy of Chichester and the earldom of Donegall.
The Protestant Telegraph was a Northern Irish newspaper founded by Noel Doherty and Ian Paisley on February 13th, 1966.
 It was noted for its Protestant fundamentalism and its attacks on the Roman Catholic Church, the Church of Ireland and the moderates within the Ulster Unionist Party, as typified by Terence O'Neill.

Question: What type of person does Terence O'Neill and Ian Paisley have in common?
Answer: leader