What is leadership?
There are several "leadership" models. The one I embrace and that seems to clearly produce the best sustained results over time (see such seminal books as Built to Last and Good to Great) is servant leadership... humble but firm team-first leadership for a greater/aspirational purpose. The best leaders demonstrate their prowess and trustworthiness (i.e., worthy of being followed by the best volunteer team members) via the three C's: Character, Competency, and Caring. A well-known Christian CEO, Max DePree (Herman Miller Company) once said: "The first responsibility of a leader is to define reality. The last is to say thank you. In between, the leader is a servant."
Leaders make a positive difference in a organization by motivating people with soft power (influence) versus force. I don't lend to textbook models much being the type of group or commodity will have require different leaders. Not to say firmness at times is not needed but this should not be the main approach.
The most effective leaders are those who are charismatic and transitional, example Martin Luther King, Jr III. A leader who can effect change must be humble, willing to serve and not be served, such as Mahatma Gandhi. That person must have conviction to the beliefs he/she espouses. and be above being bribed. The ability to delegate and hold individuals accountable to their responsibilities is important, as one person cannot have all the skill sets to succeed at everything, nor would that person have the time or energy to excel as necessary.
Which are your examples of leadership and why? Apollone Reid already called out some