Some Say There Are Almost as Many Definitions of Leadership

Some say there are almost as many definitions of leadership as there are people who have tried to define the concept. Although different definitions sound similar, they have important differences. Compare and contrast these definitions, for example:
Alistair: A leader is someone who can influence others and who has managerial authority.
Bentham: Leaders have the ability to influence a group toward the achievement of a vision or set of goals.
Cooke: Leaders exercise influence and control over other members to help a group or organization achieve the organization's goals.
Which of the following would be a leader according to Bentham's definition of leadership but would NOT be a leader according to Cooke's definition of leadership?
An executive who influences other employees to reject their company's vision of social responsibility
A manager who excels at executing clearly-defined tasks but consistently fails at tasks that are more fluid and flexible
An employee who defines his or her personal goals based on the company's goals
A division leader who wields power based on fear instead of professional duty
A corporate officer who inspires others by describing a compelling vision of the future