Laurence Ginnell (1854 – 17 April 1923) was an Irish nationalist politician, lawyer and Member of Parliament (MP) of the House of Commons of the United Kingdom of Great Britain and Ireland as member of the Irish Parliamentary Party for Westmeath North at the 1906 UK general election, from 1910 he sat as an Independent Nationalist. At the 1918 general election he was elected for Sinn Féin.In 1917 he campaigned to try and ensure the election of Count Plunkett in the Roscommon North by-election in which he defeated the IPP candidate on an abstentionist platform. Following the victory of Éamon de Valera in East Clare, while standing for Sinn Féin, on 10 July 1917, Ginnell resigned his seat in the House of Commons and joined Sinn Féin. At the Sinn Féin Ard Fheis that year, at which the party was re-constituted as a Republican party with de Valera as President, Ginnell and W. T. Cosgrave were elected Honorary Treasurers. In the 1918 general election, he was elected as a Sinn Féin MP for the Westmeath constituency, comfortably defeating his IPP challenger, and attended the proceedings of the First Dáil. He and James O'Mara were the only Teachtaí Dála (TDs) ever before to sit in a parliament. He was one of the few people to have served in the House of Commons and in the Oireachtas. Ginnell was appointed Director of Propaganda in the Second Ministry of the Irish Republic.
He was appointed the Representative of the Irish Republic in Argentina and South America by de Valera. He carried out his propaganda work here to distribute copies of the Irish Bulletin and to provide the Sinn Féin version of the conflict during the War of Independence. On the 16 August 1921 he returned home to attend the first meeting of the Second Dáil. He travelled back to Argentina some months later to serve as the Representative of the Republic there.
He opposed the Anglo-Irish Treaty that was ratified by the Dáil in January 1922, and was elected as an anti-Treaty Sinn Féin TD at the 1922 general election on the eve of the Irish Civil War.
On 9 September 1922, Ginnell was the only anti-Treaty TD to attend the inaugural meeting of the Provisional Parliament or Third Dáil. Before signing the roll Ginnell said: "I want some explanation before I sign. I have been elected in pursuance of a decree by Dáil Éireann, which decree embodies the decree of May 20th, 1922. I have heard nothing read in reference to that decree, nothing but an Act of a foreign Parliament. I have been elected as a member of Dáil Éireann. I have not been elected to attend any such Parliament. Will anyone tell me with authority whether it is …". He was at this point interrupted but resumed saying he would sign the roll and take his seat in the Assembly if the Assembly was Dáil Éireann. He was informed he was not allowed raise any such question until a Ceann Comhairle had been elected. He continued to ask questions regardless to which he got no answer including his question: "Will any member of the Six Counties be allowed to sit in this Dáil?". W. T. Cosgrave moved at this point that he be excluded from the House, Ginnell protested, and he was dragged out by force. His lawyerly sophistry was not appreciated, given that hundreds of people had already been killed in the civil war.
De Valera later appointed him a member of his "Council of State", a 12 member body set up to advise him on the deteriorating situation in the civil war.
He returned to the United States soon after this to serve as the Republic’s envoy in the country. He ordered Robert Briscoe and some of his friends to take possession of the Consular Offices in Nassau Street in New York City, then in the hands of the Free State Government, so as to obtain the list of the subscribers to the bond drive in the United States to help the struggle in the War of Independence. At the time a court case was ongoing to decide on who had the right to the funds, the newly installed Provisional Government or de Valera, as one of the three trustees and those who opposed the Treaty. Laurence Ginnell died in the United States on 17 April 1923 aged 69 years, still campaigning against the Anglo-Irish Treaty.