Quasar

A quasar is a supermassive black hole, that emits huge amounts of energy, powered by the matter that is flowing into it. A strange Habitable Zone can exist around one.

The energy source
Matter falls into a quasar and gets squeezed so much, that it generates tremendous amounts of energy, far more that it could ever generate by nuclear fusion. As it collides into the central black hole, it also spins very fast (close to the speed of light), creating one of the strongest magnetic fields in the Universe. As a result of this magnetic field, a part of this matter can get removed from the accretion disk (matter spinning fast and waiting to enter the black hole) is thrown away, into two giant beams, traveling close to the speed of light.

A quasar is deadly and unpredictable. Its light changes very fast, depending on what it is swallowing. It also has huge emissions of deadly ultraviolet, X and gamma rays, but because matter is moving so fast inside, photons lose energy traveling outside. So, the highest amount of light seems not to be deadly. Also, quasars generate massive amounts of radio waves. The power they generate (mainly their two polar beams) could be strong enough to seriously affect a galaxy.