Many aggressive and violent behavioural phenotypes (described clinically) are seen across much of the class Mammalia. Here we discuss how the early focus on explaining such behaviours with reference to specific brain regions and single monoaminergic neurotransmitters has matured into an understanding based on neurogenetic networks with different molecular constituents underlying different kinds of aggression. Some of the aminergic and peptidergic neurotransmitter targets used clinically significantly reduce bursts of aggressive and violent behaviours. However, long-term treatment strategies remain challenging for clinicians when controlling persistent aggressive syndromes. Current therapies for managing violence, at least in clinical settings, will be enhanced by preclinical experimental efforts that pinpoint more exact pharmacodynamics within neural circuits underlying specific aggressive behaviours. A comprehensive appreciation of the neuroscience of excessive aggression is necessary to begin understanding the complex framework in which patterns of community violence appear.