A serious stalker is someone who persistently follows and harasses their victim. Synonyms for serious stalker include obsessive pursuer, relentless follower, persistent harasser, and compulsive tracker. These terms describe an individual who exhibits persistent and unwavering behavior in tracking their victim, often causing a sense of fear and anxiety. Other synonyms include invasive observer, constant watcher, and tenacious shadow. These words highlight the persistent nature of a stalker and emphasize the need for victims to seek help and take necessary precautions to protect themselves from potentially harmful situations. It is important to recognize the gravity of stalking behavior and take it seriously.