Thomas Hickey (died June 28, 1776) was an Irish-born soldier who served in the French and Indian War and American Revolutionary War, and was the first Continental Army soldier to be executed for "mutiny, sedition, and treachery". Born in Ireland, Thomas Hickey came to America as a British Army soldier and fought as a combat field servant to Major-general William Johnson in the French and Indian War. He later joined the Continental army when the Revolutionary War broke out, and became part of the Commander-in-Chief's Guard, which protected General George Washington, his staff, and the Continental Army's payroll. Hickey was briefly jailed for passing counterfeit money; during this incarceration, he told another prisoner he was part of a conspiracy. He was later tried and executed for mutiny and sedition against the Continental Army. Plausible, but unverified, reports suggest that he may have been involved in an assassination plot against Washington in 1776.

Washington made a general announcement after his death:

The unhappy fate of Thomas Hickey, executed this day for mutiny, sedition, and treachery, the General hopes will be a warning to every soldier in the Army to avoid those crimes, and all others, so disgraceful to the character of a soldier, and pernicious to his country, whose pay he receives and bread he eats. And in order to avoid those crimes, the most certain method is to keep out of the temptation of them, and particularly to avoid lewd women, who, by the dying confession of this poor criminal, first led him into practices which ended in an untimely and ignominious death.

In April 1776, after the conclusion of the Boston campaign, General George Washington and the Continental Army marched to New York City and prepared for an anticipated assault on the city by the British Army. The governor of New York, William Tryon, had been driven out of the city by American forces and was compelled to seek refuge on a ship in New York Harbor. Nevertheless, the city had many Loyalist residents who favored the British side.

Thomas Hickey was a private in the Commander-in-Chief's Guard, a unit formed on March 12, 1776, to protect Washington, his staff, and the Continental Army's cash. That spring, Hickey and another soldier were arrested for passing counterfeit money. While incarcerated in Bridewell prison, Hickey revealed to another prisoner, Isaac Ketchum, (possibly overheard by two others, Isaac and Israel Youngs) that he was part of a wider conspiracy of soldiers who were prepared to defect to the British once the expected invasion came.

Arrested by civilian authorities, Hickey was turned over to the Continental Army for trial. He was court-martialed and found guilty of mutiny and sedition. He was hanged on June 28, 1776, at the corner of Chrystie and Grand Streets before a crowd of 20,000 spectators in New York. Hickey was the only person put on trial for the conspiracy. During the trial, David Mathews, the Mayor of New York City and a Loyalist, was accused of funding the operation to bribe soldiers to join the British. Although the charge was never proven, Mathews and 12 others were briefly imprisoned. The initial plan was alleged to include plans to kidnap Washington, assassinate his officers, and blow up the Continental Army's ammunition magazines. These rumors greatly damaged the reputation of Loyalists throughout the nascent United States.

In the transcript of Court Martial for the Trial of Thomas Hickey and Others on June 26, 1776, Hickey is referred to as a "private sentinel" in Washington's Life Guards, under the command of "Maj. Gibbs". There is reason to suspect this transcript is a copy made shortly after the end of the Revolutionary War when many official papers were being copied for preservation. In Harry Ward's George Washington's Enforcers (2006), he gives Hickey's rank as sergeant, and notes that Captain Caleb Gibbs was not promoted to major until June 29, 1778, two years after Hickey's trial. When enlisted soldiers are convicted, it is normal for their punishment to include a reduction to the lowest rank, private. A postwar transcript would explain why Hickey is listed at his lowest rank and Gibbs is identified at his highest rank.^{[citation needed]}

Washington's headquarters from May to June 1776 was at Richmond Hill, a suburban villa outside the city. Samuel Fraunces, a tavern keeper whose establishment was about two miles away, provided meals for the general and his officers. Washington hired a housekeeper, a 72-year-old widow named Elizabeth Thompson, who worked at Richmond Hill from June 1776 to December 1781.