The stalker

The stalker is a hostile mob that will try to attack the player while the player is not looking at it. However if the player does notice the stalker it will run and hide to shadow areas until the player is either not looking or is distracted it hates being watched, hates sunlight and soul touch's and soul lanterns the stalker does attack other hostiles but if the stalker is unable to attack you it will find a hostile mob to attack instead this would be the first mob in Minecraft to attack players and hostile mobs without an easter egg and has the intelligence to know when to strike or not