Stalking is a problem behaviour in which one individual imposes repeated unwanted contacts or communications on another, creating distress and fear. A classification is provided as a guide to assessing and managing stalkers, their victims, advising the courts and organisations, and for mental health professionals, personal safety. Threats to kill need to be taken seriously. But how seriously given such threats are often part of the common currency of everyday speech? The management of sexual offending is a specialised component of forensic psychiatry. The development and maintenance of expertise and adherence to expert guidelines requires collaboration and networking, as well as effective working with other disciplines. Forensic psychiatric assessment of terrorism can be difficult. It may be unclear whether the case actually involves terrorism, let alone what contribution mental disorder might make. Nonetheless, psychiatric assessment of the terrorism offender relies on the same basic principles of good quality assessment utilising a multiagency approach when assessing any complex criminal, or potentially criminal, behaviour involving mental disorder.