This study explores the characteristics of individuals affiliated with violent extremist milieus in Sweden, focusing on far-right, far-left, and Islamic extremist milieus. Firstly, by using a compilation of law enforcement and other Swedish population registers, we describe these milieus along a range of demographic, socioeconomic, criminal, mental health, and familial indicators. We then compare Swedish extremists to extremists globally. Our findings reveal that while demographic patterns, such as age and sex, align with international studies, significant differences emerge in areas like criminal activity, mental health prevalence, and socioeconomic factors. Compared to global data, Swedish extremists show higher levels of criminal involvement, particularly prior to radicalization, but lower prevalence of severe mental disorders. Additionally, violent Islamic extremists in Sweden exhibit a significantly higher likelihood of having extremist family members, suggesting a possible intergenerational transmission of extremist affiliation. Socioeconomic disparities are also evident, with violent far-right and violent far-left extremists displaying different educational and employment patterns compared to their international counterparts. By combining Swedish register data with international comparisons, this study highlights the importance of considering national contexts when analysing extremist profiles and emphasizes the need for comprehensive, context-based designs to prevent and counter violent extremism.