Who?

Who's that in the shadow
by the door,
A boy, a man, struck
rigid against the wall.
I turn over in my bed
and cover up my head,
Why does my imagination want me dead, dead
Who's that creeping closer to my bed,
Something's tip-tapping on the floor,
I don't like this game anymore.
Who's that breathing on my neck,
Who's that heaving in and out,

A look, a shout, a clout, I'm out.
Nothing's in the shadow anymore, more.