Overzealous fan (4)
(Other definitions for stalker that I've seen before include "Person who follows another about as if hunting prey" , "who follows a celebrity?" , "One harassing celebrity" , "Obsessive follower" , "Obsessive harasser" .)
(Other definitions for stan that I've seen before include "Laurel perhaps" , "One of the comic duo" , "Ollie's partner" , "- Laurel, comedian" , "Eminem hit; man's name" .)