When people stalk, what is the name of the mental illness that makes them do this?

Many stalking cases come out of previous relationships, and are conducted by people who are otherwise considered "normal". A sizable minority of stalking cases, typically the more severe and lengthy ones, are sometimes done out of a pathological obsession or derangement. Stalking is often a form of psychological abuse.

When people stalk, what is the name of the mental illness that makes them do this?
It's called Rejection
Reply:it's more of an obsession. it can be differnt types of mental illness that cause it. but someone can be very obsessed to the point that they stalk a person