Actors make modifications to their face, voice, and body to match standard gestural conceptions of the fictional characters they are portraying during stage performances. However, the gestural manifestations of acting have not been quantified experimentally, least of all in group-level analyses. To quantify the facial correlates of character portrayal in professional actors for the first time, we had 24 actors portray a contrastive series of nine stock characters (e.g., king, bully, lover) that were organised according to a predictive scheme based on the two statistically independent personality dimensions of assertiveness (i.e., the tendency to satisfy personal concerns) and cooperativeness (i.e., the tendency to satisfy others’ concerns). We used three-dimensional motion capture to examine changes in facial dimensions, with an emphasis on the relative expansion/contraction of four facial segments related to the brow, eyebrows, lips, and jaw, respectively. The results demonstrated that expansions in both upper- and lower-facial segments were related to increases in the levels of character cooperativeness, but not assertiveness. These findings demonstrate that actors reliably manipulate their facial features in a contrastive manner to differentiate characters based on their underlying personality traits.