Serial homicide has attracted much attention, but little empirical scientific investigation. This exploratory study reports demographic information on a large sample of serial homicide offenders (157 offenders, 608 victims), and compares a subsample of serial homicide offenses with a control group of single homicide offenses. Results show that serial homicide offenders target more women than men, and kill more strangers than family or friends. Single homicide offenders kill men and women in equal frequency, but kill family and friends more often than strangers. Serial homicide offenders kill for apparent sexual motivation more often than for any other reason, while single homicide offenders kill most often out of anger.