he was standing there, in a quiet corner of the room, who exactly was he? ghost ? demon ? why is he so mysterious

He face is completely emotionless as usual, he doesn't move, he just stares at you even though it's just a silhouette, it's still scary

You try to stop thinking about that figure by going to sleep,But you couldn't sleep and finally you opened your eyes and saw him, He's crawling up the wall, heading towards you

What would you do?