M15, the Great Pegasus Cluster (NGC 7078). More than 100,000 stars packed into a ball about 175 light-years across, about 35,000 light-years away, and about 12 billion years old, one of the oldest clusters in our galaxy. It is one of the most tightly packed globular clusters in the Milky Way: its core has collapsed, with stars crowding ever tighter toward the centre. Hidden in that crowd is Pease 1, a tiny planetary nebula found in 1928, the first ever discovered inside a globular cluster.
The core here is not burnt out to a white blob: 1-second exposures were blended into the bright centre (HDR) so individual stars show right into the middle. The star colours are real, from separate red, green and blue exposures: the old red giants glow orange and the hot horizontal-branch stars blue. No star removal, no SCNR, no hue curves.