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/
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.
An artist's illustration of the black hole at the heart of a quasar in the distant universe. The biggest black hole known to exist lives in the nearby galaxy M87. It's 2,000 times bigger than the Milky Way's supermassive black hole.