This is a Hubble Space Telescope image of a pair of star clusters that are believed to be in the early stages of merging. The clusters lie in the gigantic 30 Doradus Nebula, which is light-years from Earth. (via Merging clusters in 30 Doradus
NGC 6888 - Crescent Nebula, is a cosmic bubble about 25 ly across, blown by winds from its central, bright, massive star. NGC central star is classified as a Wolf-Rayet star (WR NGC 6888 is about 5000 light years away in the constellation Cygnus.
Star Cluster Pismis NGC Pismis 24 hangs over NGC a nebula about 8000 ly away in Scorpius. This picture showed that the brightest star in the cluster is in fact two stars in a tight binary orbit. Each star is about 100 times the Sun's mass.