Prior studies have mainly focused on the controversial issue of whether violent video games lead to aggressive behavior in real life. However, data regarding antisocial behavior while playing online are still scarce. In this study, we examined the relationship between toxicity (a form of verbal aggressive behavior directed against other players) in multiplayer online video games and several potential predictors such as personality traits, emotion reactivity, and motivations to play. A large-scale survey (n = 816) was conducted among French-speaking adult gamers, assessing video game habits, impulsivity, empathy, emotion reactivity, and motivations to play (i.e., socialization, achievement, immersion). Results showed that younger age, being male, spending a lot of time playing per week, and being highly achieving increased the likelihood of reporting toxicity and change of behavior in game. High emotional reactivity and being high in two dimensions of impulsivity (negative urgency and sensation seeking) increased the likelihood of toxic behavior. In contrast, individuals who are more empathic tended to report nontoxic behavior and individuals who play to socialize reported little change in behavior in game. Future research should address the complexity of behaviors displayed during online games—notably through experimental studies allowing direct observation of gamers while they play—and the functional connection between toxicity and several psychological, emotional, and motivational dimensions in further detail. Scientific research would also benefit from the creation and validation of a scale measuring in game, the social and antisocial behaviors.