The research aims to highlight the importance of leadership in the business field, with reference to case studies of effective and ineffective leaders. The study explains the measures which makes a leader effective and helps him to lead the followers towards success. For this purpose, study includes analysis of leadership methods, being used by two famous leaders; John Legere, CEO of T-Mobile and Bernard Hees, CEO of Kraft Heinz Company. There exist many theories and leadership styles which helps the leader to become effective and smart. An effective leader has good characteristic of leadership which enables him to achieve organizational objectives and goals on the right time. Furthermore, effective leadership enables the people to remain loyal to their leaders and become more productive and smart to let their leader progress.  Thus, the goal of the current research is to evaluate how these leadership styles and theories makes a leader effective, and why an effective leader is important for the success of an organization.