This guy at my work really scares me, and I need some help?

he knows I am bit of a loner so he sits and wait around for me to make the first move to do or say anything to him and it is HIGHLY uncomfortable. if i was to say something like, I just want to be alone, I'm dealing with some issues, I would be MORTIFIED. am I just suppose to ride it out and see what happens. he's one of the most annoying guys I have ever met. like he is the answer to my prayers or soemthing. what is this called?