This paper seeks to define the qualities of a good research library leader through a qualitative study using the lens of Aristotelian virtue theory. Narrative evidence was collected from library directors in the UK and North America on their ethical identity, how they develop excellence in their libraries, and how they deal with complex problems. A set of virtues are identified and presented in a model of a flow of influence from the leader into the organization, with beneficial effects on character, culture and social impact. The paper provides a unique perspective on library leadership and organization in the academy.