Numerous studies have linked lower levels of serum cholesterol with heightened aggression, violent crimes, and violent deaths across diverse populations, including forensic psychiatric patients, criminals, and the broad public. Interestingly, this association appears to be more pronounced in men than in women. Conversely, findings regarding serum triglycerides present a more nuanced picture, with some studies indicating heightened aggression with elevated levels and others suggesting the opposite. However, most studies have neglected to examine this phenomenon in conjunction with psychological traits. Additionally, no prior research has explored the association between serum lipid levels and different types of aggression, e.g., reactive, instrumental, or appetitive. Considering these gaps, our study aimed to assess serum cholesterol and triglyceride levels upon clinic admission and correlate them with scores from the Appetitive and Facilitative Aggression Scale (AFAS), a self-rating questionnaire assessing reactive and appetitive aggression. We conducted our investigation on a cohort of 135 forensic psychiatric patients undergoing drug addiction treatment under Section 64 of the German Criminal Code. This provision offers a nearly unique opportunity worldwide for individuals who have committed crimes under the influence of drugs or in the context of their addiction to receive specialized treatment. Using non-linear Spearman correlation analyses, we observed an inverse relationship between serum concentrations of both cholesterol and triglycerides and AFAS appetitive violence scores but not for reactive aggression. Additionally, triglyceride levels exhibited an inverse association with the prevalence of violent crimes as an index crime. In conclusion, blood lipids may affect numerous areas of health and disease beyond what is currently known, offering a potential shift in how we understand their role in aggression.