--- - |2+ Objective This research seeks to clarify the association between online trolling and sadistic personality, and to provide evidence that the reward and rationalization processes at work in sadism are likewise manifest in online trolling. Method Online respondents (community adults and university students; total N = 1,715) completed self‐report measures of personality and trolling behavior. They subsequently engaged in one of two judgment tasks. In Study 1, respondents viewed stimuli depicting scenes of emotional/physical suffering and provided ratings of (a) perceived pain intensity and (b) pleasure experienced while viewing the photos. In Study 2, the iTroll questionnaire was developed and validated. It was then administered alongside a moral judgment task. Results Across both studies, online trolling was strongly associated with a sadistic personality profile. Moreover, sadism and trolling predicted identical patterns of pleasure and harm minimization. The incremental contribution of sadism was sustained even when controlling for broader antisocial tendencies (i.e., the Dark Triad, callous‐unemotionality, and trait aggression). Conclusions Results confirm that online trolling is motivated (at least in part) by sadistic tendencies. Coupled with effective rationalization mechanisms, sadistic pleasure can be consummated in such everyday behaviors as online trolling.© 2018 Wiley Periodicals, Inc. - Journal of Personality, EarlyView.