The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area 2.5 arc minutes across, about one 24-millionth of the whole sky, which is equivalent in angular size to a 65 mm tennis ball at a distance of 100 meters. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and December 28, 1995.

Three years after the HDF observations were taken, a region in the south celestial hemisphere was imaged in a similar way and named the Hubble Deep Field South.

The similarities between the two regions strengthened the belief that the universe is uniform over large scales and that the Earth occupies a typical region in the universe (the cosmological principle).

A wider but shallower survey was also made as part of the Great Observatories Origins Deep Survey. In 2004 a deeper image, known as the Hubble Ultra-Deep Field (HUDF), was constructed from a total of eleven days of observations.

The HUDF image was at the time the most sensitive astronomical image ever made at visible wavelengths, until the Hubble Extreme Deep Field (XDF) was released in 2012.