In 1758, Charles Messier, a young French astronomer, was trying to find the comet which Edmond Halley had predicted would return in that year -- the comet we now know as Halley's Comet. While hunting for the comet, he happened across a small fuzzy patch in Taurus which looked, in a small telescope, just like a comet, but did not move among the stars from night to night, as comets do. This fuzzy patch had already been discovered by John Bevis, in 1731, but became most famous as M1, the first item in a list which Messier began to compile, of faint fuzzy objects which might be mistaken for comets.
Messier eventually observed forty-four comets, of which thirteen were independent discoveries, and twelve carry his name, in recognition of the discovery, so he was an exceptionally successful comet-hunter. Nowadays, however, what he is most remembered for is the list of faint fuzzy objects, the Messier Catalog, which he constructed. The objects on this list represent the majority of the easily observable dark-sky objects visible from northern latitudes, and include many of the most beautiful objects in the heavens.
Images of all Messier objects, including some added after Messier's death. (Wikimedia, Thierry Lombry)
(The image of M102 is not the same as elsewhere on this site, as its identification is uncertain.)