There are two big problems related to leadership today: unequal representation and high failure rates among leaders. This conceptual paper argues that commonly shared values, assumptions, and beliefs about leadership, i.e., universal leadership culture, are the common cause of both problems. After the concepts and levels related to leadership culture were explained, we introduce a multilevel, multi-actor process model named the bottleneck metaphor of leadership culture. This metaphor describes how leadership cultures are co-constructed by multiple actors based on their involvement in leader selection and reproduce themselves in groups over time based on emergent leaders' characteristics. Next, a diagnostic tool called “the leadership mirror” is proposed for organizations that want to assess their leadership culture's current state as a starting point for further interventions. Specific suggestions are made for various actors, ranging from individuals to organizations, for their possible roles in preventing undesired leadership cultures.