Globular Cluster M5 (also known as Messier Object 5 or NGC 5904) is a globular cluster in the constellation Serpens. It was discovered by Gottfried Kirch in 1702.

M5 is, under extremely good conditions, just visible to the naked eye as a faint "star" near the star 5 Serpentis. Binoculars or small telescopes will identify this cluster as non-stellar while larger telescopes will start to show individual stars, of which the brightest are of apparent magnitude 12.2.

M5 was discovered by the German astronomer Gottfried Kirch in 1702 when he was observing a comet. Charles Messier found it in 1764 and thought it a nebula without any stars associated with it. William Herschel resolved individual stars in the cluster in 1791, counting roughly 200 of them.

M5 is not to be confused with the much fainter and more distant globular Palomar 5 which is situated nearby in the sky.

Spanning 165 light-years across, M5 is one of the larger globular clusters known. The gravitational sphere of influence of M5, (ie. the volume of space where stars would be gravitationally bound to the cluster and not ripped away from it by the Milky Way's gravitational pull), has a radius of some 200 light-years.

At 13 billion years old it is also one of the older globulars associated with the Milky Way Galaxy. The distance of M5 is about 24,500 light-years away from Earth and the cluster contains more than 100,000 stars up to perhaps 500,000 according to some estimates.