Team composition research has largely focused on how the mean or variance amongst team member characteristics may influence team functioning, but such an approach fails to acknowledge that ‘difficult’ team members may have a disproportionately negative influence on the people around them, and have the potential to single-handedly impair team outcomes. In this research, we integrated the literatures on team composition and difficult employees, and offered an investigation of how four ‘difficult’ team member characteristics influence team trust, team relationship conflict, and team effectiveness, as well as how leaders may overcome these detrimental effects. Specifically, we explored the effects stemming from having team members characterized by low levels of conscientiousness, negative attitudes towards the organization, low benevolence values (i.e., one who cares little about others' needs or preferences), and low collectivistic values within an organization that endorses these values (i.e., cultural misfit). We assessed the hypothesized relationships via field survey study of action teams in a military context at three time points. Our results support the assertion that difficult team members exerted a disproportionately negative influence on team trust and team relationship conflict that emerged after several weeks of working together, and that team trust mediated the relationship between difficult member characteristics and team effectiveness. However, leaders’ collaborative conflict style attenuated the effects of difficult team members on team trust, thereby demonstrating a promising avenue for more effectively managing ‘difficult’ team members.