The Great Comet of 1811 (formally designated C/1811 F1) was a comet that was visible to the naked eye for around 260 days. In October 1811, at its brightest, it displayed an apparent magnitude of 0, with an easily visible coma. In December one length of the double tail extended for over 60 degrees. It was categorized as a Great Comet, the 54th in recorded history and one of eight in the 19th century.

In many ways the comet was quite similar to Comet Hale-Bopp. It became spectacular without passing particularly close to either the Earth or the Sun, but had an extremely large and active nucleus. It was discovered on March 25, 1811 by Honoré Flaugergues at 2.7 AU from the sun and confirmed by Jean-Louis Pons and Franz Xaver, Baron Von Zach in April.

The sightings continued until June when it was lost to solar glare . It was recovered in August as a 5th magnitude object. The comet brightened as it approached perihelion in September and its minimum distance from Earth at 1.1 AU. The comet nucleus was estimated at 30-40 km in diameter and the orbital period was calculated at 3,757 years (later adjusted to 3,065 years).

In total, the comet was visible to the naked eye for 9 months, a record it held until the appearance of Comet Hale-Bopp.

At the mid-point of War and Peace, Tolstoy describes the character of Pierre observing this comet.