As system designers, do we sometimes forget where biometrics come from? The ¿usual¿ standard biometric system model includes the biometric presentation and a biometric sensor but not users themselves. Having this model facilitates having shared vocabulary and abstraction for technologists and systems developers. However, advancing the systems science of biometric systems will require a shift towards a user-centered viewpoint. After all, without a user there can be no biometric. In this paper, we argue that it is not only appropriate, but necessary to consider users-their behavior, cognition, perception and anthropometrics-as a component of a biometric system.