someone who is completely and totally obsessed with another person to the point of insanity. They like one person for years at a time and do juvenile things such as finding their phone number out from someone else, calling them 3 times a week, driving past their house, finding out where they work, knowing every little fact about them even when they know nothing about you, memorizing their license plate number, keeping pictures and photos of them you've stolen, collecting items of theirs such as used straws, etc.

a creepy guy who knows what youre doing at all times and when he dosent hes trying to know. Someone who harrasses, annoys, provokes because of self contempt and jealousy. Is known for doing anything to get a reaction. Will go to any length because hes so f'in sad and has no life whatsoever. Bruised ego loser.

One who knows everything about someone

Anyone who has an intense interest in another person. Could encompass a wide variety of people; ranging from the innocent and idealistic to the homocidal, but in our cynical society such people are generally thought of as dangerous, especially if they are socially inept.

See instead hopeless romantic.

stalker: selective walker

Someone who looks through all your photos but doesn't comment.

Following around the person you like even though they hate you and would wish to hit you with a scalding hot frying pan if legal. Some people call this stalking. I call it love.