Thomas Taylour, 1st Marquess of Headfort KP (18 November 1757 – 24 October 1829), styled Viscount Headford from 1766 to 1795, and known as The Earl of Bective from 1795 to 1800, was an Irish peer and politician.

[1] His younger brother, Clotworthy Taylour, inherited their maternal uncle's estates and was raised to the Irish peerage.

His maternal uncle, Hercules Rowley, 2nd Viscount Langford represented County Antrim and Downpatrick in the Irish Parliament.

Subsequently, he sat as Member of Parliament for Longford Borough until 1794 and then for County Meath until 1795, when he succeeded his father as earl.

[8] Together, they were the parents of two sons and two daughters, including:[5] Headfort eloped in 1803 with the wife of Reverend Charles D. Massy (son of Sir Hugh Dillon Massy), resulting in a lawsuit, 10,000 pounds damages and, for the plaintiff, one of John Philpot Curran's most famous speeches.