The Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. Messier was a comet hunter, and was frustrated by objects which resembled but were not comets, so he compiled a list of them, in collaboration with his assistant Pierre Méchain, to avoid wasting time on them.

A similar list had been published in 1654 by Giovanni Hodierna, but had no impact and was probably not known to Messier.

The first edition covered 45 objects numbered M1 to M45. The total list published by Messier finally contained 103 objects, but the list "got an independent life" by successive additions by other astronomers, motivating the additions by side notes in Messier’s and Mechain’s texts indicating that either of them knew of the objects. The first such addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier’s side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.M102 was observed by Méchain, who communicated his notes to Messier; later, it was admitted by Méchain himself that this object does not exist, and it was simply a re-observation of M101. Some sources mention the galaxy NGC 5866 as an identification for M102, but its description does not fit with Méchain's notes.

Charles Messier (26 June 1730 – 12 April 1817) was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects". The purpose of the catalogue was to help astronomical observers, in particular comet hunters such as himself, distinguish between permanent and transient visually diffuse objects in the sky.

Messier was born in Badonviller in the Lorraine region of France, being the tenth of twelve children of Françoise B. Grandblaise and Nicolas Messier, a Court usher. Six of his brothers and sisters died while young and in 1741, his father died. Charles' interest in astronomy was stimulated by the appearance of the spectacular, great six-tailed comet in 1744 and by an annular solar eclipse visible from his hometown on 25 July 1748.

In 1751 he entered the employ of Joseph Nicolas Delisle, the astronomer of the French Navy, who instructed him to keep careful records of his observations. Messier's first documented observation was that of the Mercury transit of 6 May 1753.