Rexorian

The Rexorians are a blue energy based lifeform from the planet Rexor IV, they feel no positive emotions like love, caring and devotion, only negative ones like hate and violence (though in one seen case this may not be true and therefore may be more compassionate than believed ), they are aggressive towards humans killing a number of them as soon as the human space craft landed on their home world, they have the ability to metamorph, to join with another living organism and join with their DNA and inherit memories making them very hard to spot.