The Tánaiste (Irish pronunciation: [ˈt̪ˠaːnəʃtʲə]) is the second-most senior officer in the Government of Ireland, and acts as the deputy head of government. The Tánaiste is appointed by the President of Ireland on the advice of the Taoiseach. The current office holder is the leader of the Labour Party, Eamon Gilmore TD who was appointed on 9 March 2011.

Tánaiste was originally the Irish word for the heir of the chief (taoiseach) or king (rí), under the Gaelic system of tanistry. Before independence, the British Viceroy was sometimes referred to in the Irish language as An Tánaiste-Rí, literally 'the deputy king'.

The office was created in the 1937 Constitution of Ireland, replacing the previous office of Vice-President of the Executive Council that had existed under the Free State constitution.

The Taoiseach nominates a member of Dáil Éireann, who will also be a member of the government, to the office. The nominee then receives his seal of office from the President of Ireland in recognition of his appointment. The Tánaiste acts in the place of the Taoiseach during his or her temporary absence. In the event of the Taoiseach's death or permanent incapacitation, the Tánaiste acts in his stead until another Taoiseach is appointed. The Tánaiste is, ex-officio, a member of the Council of State. The Tánaiste chairs meetings of the government in the Taoiseach's absence and may take questions on his behalf in the Dáil or Seanad.

Gerry Adams (Irish: Gearóid Mac Ádhaimh; born 6 October 1948 in Belfast, Northern Ireland) is an Irish republican politician and Teachta Dála (TD) for the constituency of Louth. From 1983 to 1992 and from 1997 to 2011, he was an abstentionist Westminster Member of Parliament for Belfast West. He is the president of Sinn Féin, the second largest political party in Northern Ireland and the largest nationalist party. From the late 1980s onwards, Adams was an important figure in the Northern Ireland peace process, initially following contact by the then Social Democratic and Labour Party (SDLP) leader John Hume and subsequently with the Irish and British governments and then other parties. In 2005, the Provisional Irish Republican Army (IRA) indicated that its armed campaign was over and that it is now exclusively committed to democratic politics. Under Adams, Sinn Féin changed its traditional policy of abstentionism towards Oireachtas Éireann, the parliament of the Republic of Ireland, in 1986 and later took seats in the power-sharing Northern Ireland Assembly. However, Sinn Féin retains a policy of abstentionism towards the Westminster Parliament, but since 2002, receives allowances for staff and takes up offices in the House of Commons.