Sexual homicide is a crime that receives much media attention, but one that still has a relatively small research base compared to other crimes. Although the idea of someone deriving sexual gratification from or during the killing of another is an anathema to many, forensic professionals need to understand sexual homicide and the range of circumstances and motivations that lie behind it. This paper explores this complex crime: it illustrates the various definitions and labels used; it suggests that sexual homicide is rare and is committed by individuals who, although having troubled histories, may not differ from other offenders. Then, by examining the various legal and behavioural circumstances in which sexual homicide can occur, this paper illustrates the diversity of sexual homicide and presents it in a more understandable manner. Finally, the paper suggests that knowledge of this diversity is required both for investigative and clinical purposes.