Domestic homicide is the most extreme form of domestic violence and one of the most common types of homicide. The objective was to examine differences between spontaneous domestic homicide and nondomestic homicide offenders regarding demographics, psychiatric history, crime characteristics, and neuropsychological status, utilizing neuropsychological test data from forensic examinations of 153 murderers. Using standard crime classification criteria, 33% committed spontaneous domestic homicides (SDH) and 61% committed nondomestic homicides (NDH). SDH offenders were more likely to manifest psychotic disorders, but less likely to be diagnosed with antisocial personality disorder or to have prior felony convictions. SDH offenders manifested significantly worse neuropsychological impairments than NDH offenders. The mean number of victims was lower for the SDH than the NDH group and only 14% of SDH offenders used a firearm, whereas 59% of NDH offenders used a firearm. These findings corroborate the notion that spontaneous domestic homicide may represent a discernible criminological phenotype.