The dark core of personality is a recent construct that encompasses the malevolent, antagonistic, and aversive side of human nature that represents the common inner core of dark personality traits. The aim of the present study is to develop a short, multidimensional, and invariant version of the dark core of personality D70 measure. Two samples of participants were used in the current study (N = 570, M = 35.42 years, SD = 11.41, range = 18-69; N = 242, M = 30.19 years, SD = 12.78, range = 16-77). The new D25 measure was developed, consisting of five factors -- Callousness, Deceitfulness, Vindictiveness, Narcissistic Entitlement, and Sadism. All the structural models examined obtained adequate fits (1-factor, 5-factor, 5-factor bifactor, 5-factor 2nd order), but the 5-factor 2nd order model was considered the best option. Internal consistency/reliability, as measured by the alpha and omega coefficients and more traditional indicators, was mainly good. Construct validity (e.g., with moral disengagement, low self-control, and empathy measures) and criterion-related validity (e.g., with justice-involvement variables) were demonstrated. Scalar measurement invariance across gender and age was established, with male participants and younger participants scoring significantly higher than female participants and older participants. The findings provide support for the use of the D25 as a valid and reliable short multidimensional measure of the dark core of personality construct.