Really weird guy in the university?

there is this really weird guy in my university and earlier we used to have classes together, and he is sort of an idiot and a problem maker, so when we had classess togethere he would keep on staring at me (i dont know if that was an appreciating stare or a mocking stare) and whenever i would walk past him he has to always comment on something so i have to respond. He would keep saying and calling my name everyday. In short he was pretty damn annoying to me.

Once he even mentioned something like 'everyone was goin after me' when he got to know that i wasnt going to the university party (still cant say if he was mocking me because he is an idiot i told you)

So he annoyed me so much that i just told him one day 'are you crazy' and he got really offended and started calling me a ***** and later told me he felt very bad, i just told him to not talk to me anymore, and he did not.

Later we didnt have any classes together for over 6 six months, now we are having some classes together, and i have been noticing he is always sitting behind me, moving his head rather blatantly to look at me if i am around, and today i noticed he was looking at my face rather intently when i was talking to someone else sitting close it him. Few days back he even asked me about some girl (wether she came today or not)

So now i dont think i am funny to look at or someone who can be easily mocked at, plus i dont see him acting like this with any other girl, he is an idiot but he doesnt act exactly like this with any other girl. People usually call me attractive. And seriously i am getting very conscious with this guy around me, he looks at me like i am some sort of an experiment, can you guys please advise as to what he really wants from me and how can i handle him? Nobody had ever acted like this with me.