Marillion

You may not recall the moment that you asked me
But your invitation was clear
You'll pretend you've never met me but it's far to late
Now I'm here
Cause I'm the one who knows what scares you
I'm the one who loves you best
I'm the thirteenth at the table
I'm the uninvited guest
I'm the Banquo at your banquet
I'm the cuckoo in your nest
I'm your fifteen-stone first-footer
I'm the uninvited guest