Research has demonstrated, in Western nations, men and women are both perpetrators and victims of intimate partner violence (IPV). However, to the best of our knowledge, IPV and the Dark Tetrad (Machiavellianism, subclinical narcissism, subclinical psychopathy, and subclinical sadism) have not been included in this research fully. We investigated how these dark personalities influenced the perpetration of IPV in a cross-cultural study between Sweden and the United Kingdom through surveys with university students. We furthermore compared IPV perpetration with same-sex aggression of a non-romantic partner to explore sex- and aggression-specific effects. In a sample of 342 participants, our main findings were the following: (a) the only significant difference in IPV perpetration was women were more verbally aggressive; (b) men reported more verbal and physical same-sex aggression of a non-romantic partner; (c) men scored higher on all the Dark Tetrad personalities regardless of culture, while the Swedish sample scored significantly higher on subclinical narcissism and sadism; (d) the Dark Tetrad and aggression perpetration were significantly correlated; (e) different Dark Tetrad personalities predicted different forms of aggression perpetration with some gender differences; and (f) being high on subclinical psychopathy predicted most types of aggression regardless of target. Our study highlights that dark personalities engage in particular types of aggression, which helps to determine how and when distinctive personalities aggress for potential interventions.