No Escape: Dive Into a Black Hole (Infographic) by Karl Tate - When matter is compressed beyond a certain density, a black hole is created. It is called black because no light can escape from it. Some black holes are the tombstones of what were once massive stars. An enormous black hole is thought to lurk at the center of the Milky Way galaxy.
When Galaxies Collide: How The First Super-Massive Black Holes Were Born - Two black holes merge to become a supermassive black hole. It is thought that the first supermassive black hole was created 13 billion years ago, 1 billion years after the Big Bang. Image credit: Ohio State University-- Images
A binary black hole system, viewed edge-on. This pair of extremely dense objects twists and warps spacetime as the two black holes spiral in toward one another. Image Credit: Bohn, Throwe, Hébert, Henriksson, Bunandar, Taylor, Scheel (see http://www.black-holes.org/lensing) via: http://www.universetoday.com/116500/new-simulation-offers-stunning-images-of-black-hole-merger/