Stalking behavior can be associated with various mental illnesses, including:

Delusional disorder:


Characterized by false beliefs, such as believing that the victim is in love with them or is pursuing them.
Paranoid personality disorder:

Involves pervasive distrust and suspicion of others, which can lead to stalking behaviors.
Obsessive-compulsive disorder:

Involves intrusive thoughts and repetitive behaviors, such as following or spying on the victim.
Borderline personality disorder:

Characterized by unstable emotions, impulsivity, and difficulty with relationships, which can manifest as stalking behavior.
Schizophrenia:

A psychotic disorder that can cause delusions, hallucinations, and disorganized thinking, which may lead to stalking.
Erotomania:

A delusional disorder where the person believes that another person, usually a celebrity or someone unattainable, is in love with them.