You probably heard of disk 11. the creepy music disk that is not music. more of some journal thing
it came out with the other music disks. but this disk can only be obtainable in creative mode.
when the disk is playing you can hear someone sprinting. as seen in a video review of the disk there is a small mine shaft leading into a room with a red carpet.it is close to a way outside. it was night time.so there is a small chance of wolves chasing him. for the barking noises made. there is a chance of one or two endermen. and there is a chance of this having something to do with the storyline of herebrine. i know he is a troll joke. a hack or a mod.
but i think mojang may or may not add him back in the game. if he will be back he might only apear in some main places. when you are doing some quest or maybe even in dungeons. in dungeons he would be his stalker mode.
but when you are doing the quest he would act like endermen. exept he has a really powerfull sword
and teleports every 5 seconds. probably will unlock second endeing to minecraft. the other being killing the enderdragon.

these are just my ideas. don't expext them being put in the game ONLY by mojang. might be a mod. but i doubt it