Michael Collins (Irish: Mícheál Ó Coileáin; 16 October 1890 – 22 August 1922) was an Irish revolutionary, soldier and politician who was a leading figure in the early-20th century struggle for Irish independence. During the War of Independence he was Director of Intelligence of the Irish Republican Army (IRA). He served in the government of the self-declared Irish Republic as the Minister for Home Affairs and later as the Minister for Finance. He was Chairman of the Provisional Government of the Irish Free State from January 1922 and commander-in-chief of the National Army from July until his death in an ambush in August 1922, during the Civil War.

Collins was born in Woodfield, County Cork, the youngest of eight children. He moved to London in 1906 to become a clerk in the Post Office Savings Bank at Blythe House. He was a member of the London GAA, through which he became associated with the Irish Republican Brotherhood and the Gaelic League. He returned to Ireland in January 1916 and fought in the Easter Rising. He was taken prisoner and held in the Frongoch internment camp as a prisoner of war, but he was released in December 1916.

Collins subsequently rose through the ranks of the Irish Volunteers and Sinn Féin. He was elected as MP for South Cork in December 1918. Sinn Féin's elected members (later known as TDs) formed an Irish parliament, the First Dáil, in January 1919 and declared the independence of the Irish Republic. Collins was appointed Minister for Finance. In the ensuing War of Independence, he was Director of Organisation and Adjutant General for the Irish Volunteers, and Director of Intelligence of the IRA. He gained fame as a guerrilla warfare strategist, planning many successful attacks on British forces together with 'the Squad', such as the "Bloody Sunday" assassinations of key British intelligence agents in November 1920.

After the July 1921 ceasefire, Collins was one of five plenipotentiaries sent by the Dáil cabinet at the request of Éamon de Valera, to negotiate peace terms in London. The resulting Anglo-Irish Treaty, signed in December 1921, would establish the Irish Free State but depended on an oath of allegiance to the Crown. De Valera and other republican leaders found this clause of the treaty most difficult to accept. Collins viewed the treaty as offering "the freedom to achieve freedom", and helped persuade a majority of the Dáil to ratify the treaty. A provisional government was formed under his chairmanship in early 1922. During this time he secretly provided support for an IRA offensive in Northern Ireland. It was soon disrupted by the Irish Civil War, in which Collins was commander-in-chief of the National Army. He was shot and killed in an ambush by anti-Treaty forces in August 1922.

Collins was born in Woodfield, Sam's Cross, near Rosscarbery, County Cork, on 16 October 1890, the third son and youngest of eight children. His father, Michael John (1815–1897), was a farmer and amateur mathematician, who had been a member of the Irish Republican Brotherhood (IRB). The elder Collins was 60 years old when he married Mary Anne O'Brien, then 23, in 1876. The marriage was apparently happy. They brought up eight children on a 90-acre (36 ha) farm called Woodfield, which the Collins family had held as tenants for several generations. Michael was six and a half years old when his father died. After the death of her husband, Mary Anne had the small family home rebuilt in 1899–1900 as Woodfield House, a much larger dwelling. Michael Collins (the younger) believed his family were descendants of the Uí Chonaill Gabra.

He was a bright and precocious child with a fiery temper and a passionate feeling of Irish patriotism. He named a local blacksmith, James Santry, and his headmaster at Lisavaird National School, Denis Lyons, as the first nationalists to personally inspire his "pride of Irishness". Lyons was a member of the IRB, while Santry's family had participated in, and forged arms for, the rebellions of 1798, 1848 and 1867. There are a number of anecdotal explanations for the origin of his nickname "the Big Fellow". His family claim that he was called this as a child, as a term of endearment for an adventurous and bold youngest brother. The nickname was established in his teens, long before he became a political or military leader.^{[citation needed]}

At the age of thirteen he attended Clonakilty National School. During the week he stayed with his sister Margaret Collins-O'Driscoll and her husband Patrick O'Driscoll, while at weekends he returned to the family farm. Patrick O'Driscoll founded the newspaper West Cork People and Collins helped out with general reporting and preparing the issues.

Leaving school at fifteen, Collins took the British Civil Service examination in Cork in February 1906 and moved to the home of his sister Hannie in London, where he became a boy clerk in the Post Office Savings Bank at Blythe House. In 1910 he became a messenger at a London firm of stockbrokers, Horne and Company. While living in London he studied law at King's College London but did not finish. He joined the London GAA and, through this, the IRB. Sam Maguire, a republican from Dunmanway, County Cork, introduced the 19-year-old Collins to the IRB. In 1915 he moved to work in the Guaranty Trust Company of New York where he remained until his return to Ireland the following year joining part-time Craig Gardiner & Co, a firm of accountants in Dawson Street, Dublin.