Henry Grattan (3 July 1746 – 6 June 1820) was an Irish politician. He was a member of the Irish House of Commons. He wanted changes such as Catholic Emancipation and more self government for the kingdom. He did not believe that Ireland and Great Britain should become a single country. He was one of the people who were most important in creating the constitution of 1782. This gave Ireland self-government. He was also important in ending Poynings law of 1494 and the Declaratory Act of 1720.