A person who seems to stalk you on the world wide web, always first to comment/reply to any status update, tweet, blog posted by you. Family would assume you are the closest of friends, but in actuality you barely know this person. Band members or other public figures are frequent prey to this kind of predator.
In some cases, when your social life has become breached and a parent has become your facebook friend; this person is almost always said parent, which tends to discourage you from posting all together.
"I am being punished so hard right now by my top commenter on facebook. This 40 year old lady I met once in Utah has an off-the-wall "See More" comment for everything I post, she's a total status killer!"
See also: Status Killer, Punisher, "See More"
Alternate Example: "Oh man, I had the craziest night last night. I wanted to post a pic but "top commenter" would be all over it, I can't let him/her in like that..."