In order to understand the phenomenon of stigma in different populations (e.g., different ethnicities, different diseases, and different conditions), this Special Issue collects papers from around the world to illustrate the stigma phenomenon. After a rigorous process of peer review, a total of 24 papers were published and included in the Special Issue. These papers were contributed from different continents and countries, including the Americas (e.g., United States), Europe (e.g., Finland), and Asia (e.g., Saudi Arabia). Therefore, the diversity of ethnicity was ensured in the Special Issue. Moreover, these papers address different stigmatized populations/conditions (e.g., mental illness, obesity, public housing, homosexuality, and transgender). The most discussed populations were those with mental illness and those with obesity/overweight. However, additional evidence on the stigma topic is still needed. Specifically, future studies could consider the following directions to explore in depth the issues of stigma in different populations: (1) using longitudinal designs to understand the temporal or causal relationship between stigma and other related psychosocial factors; (2) designing treatment programs to fight stigma—this could be carried out in healthcare providers, healthcare trainees, the public, caregivers, and the stigmatized populations.