RE: Super Cool Science S#!t #24 - The Destroyer of Worlds
Nice post! One of the first I read after my return from vacation ^^
As stated above, black holes are typically formed when high-mass stars collapse under their own gravity.
There are also the hypothetical primordial black holes that were there from the early universe days. But no trace of those so far, in contrast to more normal black holes that have been observed.
PS: you may be interested in some black hole posts I wrote in the past too (too lazy to dig the links :p )