Who is Graz'zt?!?!! Ps4SE

Im losing my mind ober this, its this hyge argonian with vilkas's(?) voice and hes completely overpowered I have no clue where he's from or how he ended up on my ps4, and im not mad but i have no clue how to find him again after parting ways???? Who is this man???????

EDIT: THERE ARE MORE GHOST PEOPLE ALL AROUND THE WORLD??? BY IVARSTEAD, RORIKSTEAD? IM LOSING MY MIND