This list of black holes (and stars considered probable candidates) is organized by mass (including black holes of undetermined mass); some items in this list are galaxies or star clusters that are believed to be organized around a black hole.
As of February 2019[update], 10 mergers of binary black holes have been observed.
In addition, one neutron star merger has been observed (GW170817), forming a black hole.
In addition, over 30 alerts have been issued since April 2019, of black hole merger candidates.
These are listed above in the section Black holes detected by gravitational wave signals.