The Business Dictionary defines a manager as: "An individual who is in charge of a certain group of tasks, or a certain subset of a company. A manager often has a staff of people who report to him or her." By this definition, a manager may or may not have subordinates. For instance, a general manager has subordinates because he or she is responsible for organizing and leading an entire company. Human resource managers also deal with personnel.

A number of types of managers, though, may work alone or with subordinates—depending upon the size of the business. For example, financial managers are responsible for the collection, organization, and payment of money. In a small company, the financial manager may be able to handle the workload alone, while in a larger company help may be needed. Marketing managers deal with product research, advertising, and other facets of marketing, and this may or may not require additional personnel depending on the size of the operation. Operations managers are concerned with efficiency within an organization, and in a small business one person can handle this task.

An employee of a business could indeed be considered, and labeled, a manager despite the absence of subordinate employees working under the individual in question. The determining factor usually involves the nature of the tasks for which the employee is responsible. Not all management-level responsibilities require multiple personnel. If an individual is trusted with important responsibilities, such as over corporate strategy, operation of expensive and essential machinery, or documentation required by government agencies, such as for environmental protection, he or she could be given the title of manager. Whether that individual has staff below him or her is immaterial. In the world of government relations/lobbying, for instance, many employees of large corporations dependent upon government contracts are assigned to lobby both executive and legislative branches of government on behalf of their employer. These government relations specialists are routinely given the title of "manager" both in recognition of the importance of their work to the corporations that employ them and to give these employees the cachet necessary to secure meetings with important government officials, such as members of Congress and their staffs. The government relations specialists, however, do not have staffs, although they may share an administrative assistant. 

In conclusion, managers without subordinates are still managers because of the importance of their individual contributions and because of the necessity of providing such managers job titles commensurate with the levels of people with whom they must work. 

There are situations in which an employee without subordinate employees might be considered a manager.  Bear in mind that human resources are only one aspect of management. Managers are called upon to manage time, materials, information, and/ or money. If they have control over and responsibility for these resources, it is reasonable to call them managers. A finance department might have just one employee, who is the Chief Financial Officer. He or she is often considered a management employee because...