Tricorn pirate hat, also called Cavalier hat, is a style of hat that was popular during the late 17th century and 18th century, falling out of style shortly before the French Revolution. At the peak of its popularity, the Tricorn hat was worn as civilian dress and as part of military and naval uniforms. Its distinguishing characteristic was a practical one, the turned up portions of the brim formed gutters that directed rainwater away from the wearers face, depositing most of it over his shoulders. Before the invention of specialized rain gear, this was a distinct advantage.

The black colored Tricorn hat has a rather broad brim, pinned up on either side of the head and at the back, producing a triangular shape. The hat was typically worn with the point facing forward, though it was not at all unusual for soldiers, who would often rest a rifle or musket on their left shoulder, to wear the Tricorne hat pointed to the left to allow better clearance. The crown is low, unlike the steeple hats worn by the Puritans or the top hat of the nineteenth century.

Cavaliers hats ranged from the very simple and cheap to the extravagant, occasionally incorporating gold or silver lace trimming and feathers. In addition, military and naval versions usually bore a cockade or other national emblem at the front. The Cavalier hat later evolved into the bicorne and eventually the cocked hat.

Tricorn hats survive today as part of the traditional dress of the Chelsea Pensioners, the Guardia Civil and the Old Guard Fife and Drum Corps of the United States Army.

A black feathered Tricorn hat is worn by the Lord Mayor of the City of London for all ceremonials and is in evidence at the annual Lord Mayors Show in November, when the newly elected Lord Mayor enthusiastically waves it at the crowds.

In the United States, the Tricorne hat is associated with the American Revolution and American Patriots of that era, especially Minutemen Participants in reenactment events often don Cavaliers hats, and they also can be seen in sports culture as worn by fans of teams with Revolutionary names, such as the New England Patriots, the New England Revolution, the United States mens national soccer team, the University of Massachusetts and the George Washington University.

In France, synagogue officiants wear the Tricorne hat on formal occasions.