Immigrant entrepreneurs are different, and they are everywhere. They can be unambiguously distinguished from entrepreneurs without a migration background. They operate under distinct conditions and respond to unique opportunities and challenges. They have specific motivational, economic, and social resources at their disposal, for example, ethnic solidarity and international networks. Their knowledge of languages and cultures, as well as the high pressure to integrate themselves into a new society, can be factors that stimulate entrepreneurship and innovation. It is hard to find countries with no immigrant entrepreneurs. In many places like the United States, Canada, or South East Asia, they play a substantial economic role. The ubiquity, dynamism, and significance of immigrant entrepreneurs has led to a spate of research projects since the 1990s, especially by economic sociologists and ethnologists, but also by management scholars and historians. On the basis of their work, the article distinguishes six different ideal types of immigrant entrepreneurs, even though these categories are neither clear-cut nor mutually exclusive. Necessity entrepreneurs react to blocked careers in other areas and often set up small, precarious businesses, out of which in exceptional cases more viable companies emerge. Diaspora merchants are part of commercial networks of people with the same ethnic background who live in foreign countries and trade with each other. Transnational entrepreneurs are not necessarily part of networks and do not always engage in mercantile activities. This category also encompasses individual actors and industrial activities. They are characterized by the ability to mobilize resources in several countries and facilitate activities between different countries. Middleman minorities stand between the majority society and third parties, often minorities. They fill niches that are left by indigenous businesses, which consider these areas as unattractive. Entrepreneurs in ethnic enclave economies live and work with their co-ethnics in neighborhoods defined by their group. Their main function is to cater to their own communities, often with ethnic products such as food or publications from their countries of origin. Refugee entrepreneurs leave their home country involuntarily, often driven out by violence and expropriation. In most cases their emigration is unprepared. Starting conditions in the country of destination are unfavorable. Conversely, the pressure for social integration is pronounced and can act as an impulse for self-employment. There are, however, cases in which refugees are consciously patronized or even summoned by the governments of the receiving countries, turning them into a highly privileged group.