There is no human Leader, there is no human power capable of opening the door to conquer or dominate my heart, neither with cleverness nor with violence.      J. M. Arizmendiarrieta. Reflections. p. 46

Victor Vroom

Victor Vroom is known for his expectancy theory of motivation. The theory is no longer fashionable (yes, science has fashions like clothes) although it could be a great theory to explain many phenomena including unhappiness. But Vroom mainly inspired me by his little known contingency theory of participation. There is hardly any paper I would not quote it. Participation is our inherent human feature like language aquisition, but Vroom goes beyond this and enumerates 11 factors that help us develop this function. 

His paper "Educating managers for decision making and leadership" is one of the most recent one on the topic.