The faces we encounter throughout our lives make different impressions on us: Some are remembered at first glance, while others are forgotten. Previous work has found that the distinctiveness of a face influences its memorability--the degree to which face images are remembered or forgotten. Here, we generalize the concept of face memorability in a large-scale memory study. First, we find that memorability is an intrinsic feature of a face photograph--across observers some faces are consistently more remembered or forgotten than others--indicating that memorability can be used for measuring, predicting, and manipulating subsequent memories. Second, we determine the role that 20 personality, social, and memory-related traits play in face memorability. Whereas we find that certain traits (such as kindness, atypicality, and trustworthiness) contribute to face memorability, they do not suffice to explain the variance in memorability scores, even when accounting for noise and differences in subjective experience. This suggests that memorability itself is a consistent, singular measure of a face that cannot be reduced to a simple combination of personality and social facial attributes. We outline modern neuroscience questions that can be explored through the lens of memorability.