Thomas Fitzsimons was an American Merchant and a busy statesman from Philadelphia, Pennsylvania. Fitzsimons represented the state in the U.S Congress, Continental Congress, as well as the Constitutional Convention.

Born in 1741 in the fatherland of Ireland, Fitzsimons moved to Philadelphia in around 1760. At that time, he started to work as a mercantile house clerk. Only a year after he moved from Ireland and during his professional career, he got married to Catherine Meade around the 23rd of November 1761. Fitzsimons started to work together with George, his brother in law. The started setting up business in the trading sector of West Indies and their partnership was quite successful, even up until 41 years later.

Fitzsimons started to support the Whig position during the Revolution period. He even started to be positioned as home guards company's captain, but the 1776 Battle of Trenton was the only report that mentioned their support for the battle. Afterward, Fitzsimons didn't engage in the field battle but he started to provide money, supply, and even ships for the armed forces from Pennsylvania.

Fitzsimons started to consider political career and change around 1782, where he became Continental Congress delegate. In 1783, he also delegated for the same object. His political career and activities were getting busier as he started to enter the House of Representative in Pennsylvania around 1786 and also 1787. In 1878, he was even a delegation for the Constitutional Convention of the US Government. He managed to provide quite significant influence for the government, although he might not be the popular members of the convention. He didn't agree on slavery and he supported the idea of taxing export and imports. He also agreed on supporting the national government and also providing the similar treatments and power for the senate and the house. He was included in the Catholic Constitution signers – there were only two of them - that agreed on and signed the United States Constitution.

Fitzsimons served in the House first three sessions after the Constitution was set up. During the re-election period in 1794, he failed to achieve the same success and lost to John Swanwick that won the vote for around 57% of the total count. Fitzsimons belonged to the Federalist Party that that time, and the public didn't favor the Federalist so much at that time. They blamed the party for the suppression of the Whiskey Rebellion, which led to them blaming him in the end.

After his loss, Fitzsimons left political platform, but stayed active in his business as well as his civic activities. He became the Chamber of Commerce's president for Philadelphia state as well as the North America Bank's director. He was also active to be the Pennsylvania University trustee. In fact, he was the North America Bank and he provided support to set up and establish the Georgetown College.

Thomas Fitzsimons passed away on the 26th of August 1811. He passed away in Philadelphia and buried in Catholic Church of St. Mary, which is now the important part of the Independence National Historical Park.