Online video games afford co-play and social interaction, often anonymous, among players from around the world. As predicted by the social identity model of deindividuation effects, undesirable behavior is not uncommon in online gaming environments, and online harassment has become a pervasive issue in the gaming community. In this study, we sought to determine what personality traits and game-related variables predicted two types of online aggression in video games: general harassment (e.g., skill-based taunting, insulting others' intelligence) and sexual harassment (e.g., sexist comments, rape threats). Men who play online video games (N = 425) participated in an anonymous online survey. Social dominance orientation and hostile sexism predicted higher levels of both sexual harassment and general harassment in online games. Game involvement and hours of weekly gameplay were additional predictors of general harassment. We discuss implications of online social aggression and online sexual harassment for online gaming. We also apply our findings to the broader understanding of online harassment, cyberaggression, cyberbullying, and other forms of online hostility in computer-mediated communication contexts. Aggr. Behav. 42:513-521, 2016. © 2016 Wiley Periodicals, Inc.