The Willowbrook Hepatitis Study is one of the best-known examples of unethical medical research, but the research has always had defenders. One of the more intriguing defenses continually used was that critics did not know the researchers on the study and, therefore, could not assess their ethics. This essay traces the appeal to the researchers’ characters across published research and archival sources from the 1960s through today. These appeals reflect the observation as old as Aristotle that one of the most (...) potent modes of persuasion is ethos or character. The specific types of character in these appeals develop out of the paternalistic nature of clinical and research practice in the mid-twentieth century. If the individual physician is the locus of medical judgment, then the physician’s character becomes a key concern for bioethics. These appeals still appear and have implications for bioethics in the present day. (shrink)