List of most massive star clusters

Below are lists of the most massive known star clusters in solar masses (M_☉) and sorted in descending order.

Globular cluster masses can be determined by observing the proper motion of nearby stars influenced by the cluster or by estimating the cluster's relaxation time.

The masses of open star clusters can be estimated by measuring the falloff of radial and tangential velocities of surrounding stars at a particular distance.

• List of largest star clusters

• The young cluster RMC 136a European Southern Observatory
• Mayall II Messier Objects
• Monster Super Star Cluster Discovered In Milky Way ScienceDaily