Thomas FitzSimons was an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 merchant and statesman of Philadelphia, Pennsylvania

Philadelphia, Pennsylvania

Philadelphia is the largest city in the Commonwealth of Pennsylvania and the county seat of Philadelphia County, with which it is coterminous. The city is located in the Northeastern United States along the Delaware and Schuylkill rivers. It is the fifth-most-populous city in the United States,...

. He represented Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 in the Continental Congress

Continental Congress

The Continental Congress was a convention of delegates called together from the Thirteen Colonies that became the governing body of the United States during the American Revolution....

, the Constitutional Convention

Philadelphia Convention

The Constitutional Convention took place from May 14 to September 17, 1787, in Philadelphia, Pennsylvania, to address problems in governing the United States of America, which had been operating under the Articles of Confederation following independence from...

, and the U.S. Congress

United States House of Representatives

The United States House of Representatives is one of the two Houses of the United States Congress, the bicameral legislature which also includes the Senate.The composition and powers of the House are established in Article One of the Constitution...

.
Fitzsimons' ancestry has not been proved, but one thought is that Fitzsimons was born at Ballikilty, north Co. Wexford

Wexford

Wexford is the county town of County Wexford, Ireland. It is situated near the southeastern corner of Ireland, close to Rosslare Europort. The town is connected to Dublin via the M11/N11 National Primary Route, and the national rail network...

, Leinster

Leinster

Leinster is one of the Provinces of Ireland situated in the east of Ireland. It comprises the ancient Kingdoms of Mide, Osraige and Leinster. Following the Norman invasion of Ireland, the historic fifths of Leinster and Mide gradually merged, mainly due to the impact of the Pale, which straddled...

 province, Ireland, in October, 1741. He was a member of a collection of Irish families with the name "Fitzsymons" and it variants. In the mid-1750s he immigrated to Philadelphia where his father soon died.